One new α-pyrone and one new fatty acid derivative from mangrove-derived fungus Phomopsis sp. HYP11

One new α-pyrone derivative (S)-3-(4-methoxy-3-methyl-2-oxo-2H-pyran-6-yl)butyl acetate (1) and one new fatty acid derivative (4S,5S)-5-acetoxy-4-hydroxyhexanoic acid (2), along with six known compounds (3–8) were obtained from the mangrove-derived fungus Phomopsis sp. HYP11. Their structures and absolute configurations were determined by detailed 1D and ²D NMR, HR-ESI-MS spectral, and quantum chemical electronic circular dichroism (ECD) calculations. Compounds 2, 3, 5, 6 and 8 showed antioxidant activity with the IC₅₀ values range of 0.09–0.67 mM, especially compounds 5 and 6 showed stronger antioxidant activity than the positive control trolox (IC₅₀ = 0.29 mM). Compound 8 showed weak antagonistic effect on Ralstonia solanacearum with the MIC value of 50 μg/mL.     

Xylarianins A-D from the endophytic fungus Xylaria sp. SYPF 8246 as natural inhibitors of human carboxylesterase 2

Eighteen secondary metabolites were isolated from the fermentation broth of the endophytic fungus Xylaria sp. SYPF 8246, including four new compounds, xylarianins A-D (1–4), three new natural products, 6-methoxycarbonyl-2′-methyl-3,5,4′,6′-tetramethoxy-diphenyl ether (5), 2-chlor-6-methoxycarbonyl-2′-rnethyl-3,5,4′,6′-tetramethoxy-diphenyl ether (6), and 2-chlor-4′-hydroxy-6-methoxy carbonyl-2′-methyl-3,5,6′-trimethoxy-diphenyl ether (7), and eleven known compounds (8–18). Their structural elucidations were conducted by using 1D and 2D NMR, HRESIMS, and Rh₂(OCOCF₃)₄-induced electronic circular dichroism (ECD) spectra analyses. The integrated ¹H and ¹³C NMR data of three new natural products 5–7 were reported for the first time. All the isolated compounds were assayed for their inhibitory activities against human carboxylesterase 2 (hCE 2). Compounds 1, 5–9, and 18 displayed significant inhibitory activities against hCE 2 with IC₅₀ values of 10.43 ± 0.51, 6.69 ± 0.85, 12.36 ± 1.27, 18.25 ± 1.78, 29.78 ± 0.48, 18.86 ± 1.87, and 20.72 ± 1.51 µM, respectively. The interactions between compounds 1 and 5 with hCE 2 were anaylzed by molecular docking.     

Synthesis of a ‘direct-linked’ C-disaccharide from a pyranulose glycoside

Syntheses of five ‘direct linked’ C-disaccharides 8a–e were reported. The (Et₃SiH/BF₃·Et₂O) reduction of pyranulose glycoside 1 yielded (6S)- and (6R)-6-(2,3,5-tri-O-benzoyl-β-d-ribofuranosyl)pyran-3(2H,6H)-one (2a and 2b) in a ratio of ca. 2:1 and in 88% combined yield. The absolute stereochemistry of each was determined from its CD spectrum. The reduction of 2a with NaBH₄ in methanol afforded two allylic alcohols 6a and 6b in 14 and 73% yield, respectively. The reduction of 2b with NaBH₄ afforded 6c and 6d in 30 and 56% yield, respectively. Cis hydroxylation of the double bond in compounds 6a–d with osmium tetroxide gave 7a–e. The stereoisomers 7a–e were separated and their configuration was established by ¹H NMR spectroscopy. Debenzoylation of compounds 7a–e with aqueous sodium carbonate produced deprotected C-disaccharides 8a–e.     

Conformations of the d-glucarolactones and d-glucaric acid in solution

The conformations of d-glucaric acid (1), d-glucaro-1,4-lactone (2), d-glucaro-6,3-lactone (3), and d-glucaro-1,4:6,3-dilactone (4) in solution were investigated by ¹H-n.m.r. and ¹³C-p.F.t., n.m.r. spectroscopy. The solvents used were deuterium oxide, methanol-d₄, and dimethyl sulfoxide-d₆, and praseodymium chloride was employed as a lanthanide shift-reagent. For 2, it was found that the conformational equilibrium ³E(d)

E₃(d) exists in solution, and that the OH-5 group tends to occupy the position over the lactone ring in the favored E₃(d),gg conformation. The n.m.r. data for 3 indicated that the conformational equilibrium is shifted in favor of the ⁴E(d)

E₄(d),gt conformation in solution. The dienvelope conformation ³E:E₄(d) was found to be the favored conformation of 4. For 1, a conformational equilibrium between one planar, zigzag form and two sickle forms was indicated by the n.m.r. data observed. ¹³C-N.m.r. spectroscopy proved to be a convenient method for monitoring the lactonization of 1, and the hydrolysis of its lactones. Lactones other than 2–4 were not found in solutions prepared from 1–4, either during their mutarotation or after equilibration at 30°.     

Stereoselective epoxidation of divinylmethanol: A synthetic approach to the pentitols

Peroxy-acid epoxidation of divinylmethanol (9), followed by acetylation afforded the acetylated monoepoxides 1 and 2 having the erythro (53%) and threo (47%) configurations. Peroxy-acid epoxidation of 1 and 2 yielded the acetylated diepoxides 3 (erythro-erythro, 36%) and 4 (erythro-threo, 64%) (from 1), and 4 (erythro-threo, 47%) and 5 (threo-threo, 53%) (from 2). Relative configurational assignments were made to 1–5 on the basis of (a) ¹H-n.m.r. chemical-shift and coupling-constant data, (b) the observation that 1 gave only 3 and 4, and that 2 gave only 4 and 5 on epoxidation, and (c) the fact that 3–5 separately undergo epoxide-ring opening preferentially at their primary carbon atoms with acetate ion in acetic anhydride, to afford the penta-acetates of ribitol, dl-arabinitol, and xylitol, respectively, as major products. Epoxide-ring formation favours the erythro configuration when either peroxy acids or tert-butyl hydroperoxide with catalytically active Ti⁴⁺, V⁵⁺, or Mo⁶⁺ complexes are employed as epoxidation reagents. However, the diastereoselectivities characterising the epoxidations and the regioselectivities governing the epoxide-ring openings are not sufficiently high to constitute an attractive synthesis of either ribitol, dl-arabinitol, or xylitol from divinylmethanol.

     

C15 acetogenins with antistaphylococcal activity from the red alga Laurencia glandulifera

Five new C₁₅ eight-membered cyclic ethers (1, 3–6) with a characteristic terminal cis ene–yne moiety, along with the previously reported acetylenic chloro diol (2) were isolated from the organic extract of the red alga Laurencia glandulifera, collected at Crete island in South Greece. Full assignment of all ¹H and ¹³C resonances were carried out by extensive analysis of their NMR spectra. All metabolites were tested for their antistaphylococcal activity and the minimum inhibitory concentrations (MICs) of 2–5 were in the range of 8–256 μg/ml.     

Regulation of Ca2+ signaling by acute hypoxia and acidosis in cardiomyocytes derived from human induced pluripotent stem cells

AimsThe effects of acute (100 s) hypoxia and/or acidosis on Ca²⁺ signaling parameters of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are explored here for the first time.Methods and results1) hiPSC-CMs express two cell populations: rapidly-inactivating I_Ca myocytes (τ_i<40 ms, in 4–5 day cultures) and slowly-inactivating I_Ca (τ_i ≥ 40 ms, in 6–8 day cultures). 2) Hypoxia suppressed I_Ca by 10–20% in rapidly- and 40–55% in slowly-inactivating I_Ca cells. 3) Isoproterenol enhanced I_Ca in hiPSC-CMs, but either enhanced or did not alter the hypoxic suppression. 4) Hypoxia had no differential suppressive effects in the two cell-types when Ba²⁺ was the charge carrier through the calcium channels, implicating Ca²⁺-dependent inactivation in O₂ sensing. 5) Acidosis suppressed I_Ca by ∼35% and ∼25% in rapidly and slowly inactivating I_Ca cells, respectively. 6) Hypoxia and acidosis suppressive effects on Ca-transients depended on whether global or RyR2-microdomain were measured: with acidosis suppression was ∼25% in global and ∼37% in RyR2 Ca²⁺-microdomains in either cell type, whereas with hypoxia suppression was ∼20% and ∼25% respectively in global and RyR2-microdomaine in rapidly and ∼35% and ∼45% respectively in global and RyR2-microdomaine in slowly-inactivating cells.ConclusionsVariability in I_Ca inactivation kinetics rather than cellular ancestry seems to underlie the action potential morphology differences generally attributed to mixed atrial and ventricular cell populations in hiPSC-CMs cultures. The differential hypoxic regulation of Ca²⁺-signaling in the two-cell types arises from differential Ca²⁺-dependent inactivation of the Ca²⁺-channel caused by proximity of Ca²⁺-release stores to the Ca²⁺ channels.     

Hydrolysis of neutral phosphate and phosphonate esters catalysed by Co2+-chelates of tris-imidazolyl phosphines

The hydrolysis of two neutral phosphate esters, (tris-2-pyridylphosphate and tris-p-nitrophenylphosphate, 5 and 4 respectively) and a phosphonate ester (ethyl-p-nitrophenylmethylphosphonate (6)) were studied in the presence of Co²⁺-complexes of two tris- imidazolylphosphines. In the hydrolyses of both 5 and 6, the Co²⁺-complex of bis-[4,5-diisopropyl- imidazol-2-yl]imidazole-2-yl phosphine (2) appears to act as the anionic form, generated by ionization of a Co²⁺-bound H₂O having a pK_a of ～8 at 37 °C in 80% ethanol-H₂O. On the other hand, the Co²⁺-complex of bis-[4,5-diisopropylimidazol-2-yl]-4(5)- hydroxyethylimidazol-2-yl phosphine (3) catalyses the hydrolyses of 5 and 6 with an activity which increases linearly with pH. In this case, the active form of Co²⁺:3 has a pK_a in excess of 8.3 which apparently obtains from ionization of the Co²⁺- associated hydroxyethyl group. Evidence is presented that Co²⁺:3 functions as a general base catalyst in the hydrolysis of 5.     

Synthesis,spectral analysis and in vitro microbiological evaluation of 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones as a new class of antibacterial and antifungal agents

In the present work, a new series of bis hybrid heterocycle comprising both piperidine and thiohydantoin nuclei together namely 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones 46–60 was synthesized by the treatment of the respective thiosemicarbazones 31–45 with chloroethyl acetate and anhydrous sodium acetate in refluxing ethanol for 4 h and were characterized by melting point, elemental analysis, MS, FT-IR, one-dimensional NMR (¹H, D₂O exchanged ¹H and ¹³C), two dimensional HOMOCOSY and NOESY spectroscopic data. In addition, the title compounds were screened for their antimicrobial activities against a spectrum of clinically isolated microbial organisms. Compounds 47–50, 52–55 and 57–60 with fluoro, chloro, methoxy or methyl functions at the para position of phenyl rings attached to C-2 and C-6 carbons of piperidine moiety along with and without methyl substituent at position C-3 of the piperidine ring exerted potent biological activities against Staphylococcus aureus, β-Hemolytic streptococcus, Vibrio cholerae, Escherichia coli, Pseudomonas aeruginosa, Aspergillus flavus, Candida albicans, Candida 6 and Candida 51 at a minimum inhibitory concentration.     

Synthesis and anti-inflammatory activity of sulfonamides and carboxylates incorporating trimellitimides: Dual cyclooxygenase/carbonic anhydrase inhibitory actions

Trimellitimides 6–21 were prepared and investigated in vivo for anti-inflammatory and ulcerogenic effects and in vitro for cytotoxicity. They were subjected to in vitro cyclooxygenase (COX-1/2) and carbonic anhydrase inhibition protocols. Compounds 6–11 and 18 exhibited anti-inflammatory activities and had median effective doses (ED₅₀) of 34.3–49.8 mg kg⁻¹ and 63.6–86.6% edema inhibition relative to the reference drug celecoxib (ED₅₀: 33.9 mg kg⁻¹ and 85.2% edema inhibition). Compounds 6–11 and 18 were weakly cytotoxic at 10 μM against 59 cell lines compared with the reference standard 5-fluorouracil (5-FU). Compounds 6–11 had optimal selectivity against COX-2. The selectivity index (SI) range was >200–490 and was comparable to that for celecoxib [COX-2 (SI) > 416.7]. In contrast, compounds 12, 13, and 16–18 were nonselective COX inhibitors with a selectivity index range of 0.92–0.25. The carbonic anhydrase inhibition assay showed that sulfonamide incorporating trimellitimides 6–11 inhibited the cytosolic isoforms hCA I and hCA II, and tumor-associated isoform hCA IX. They were relatively more susceptible to inhibition by compounds 8, 9, and 11. The K_I ranges were 54.1–81.9 nM for hCA I, 25.9–55.1 nM for hCA II, and 46.0–348.3 nM for hCA IX. © 2018 Elsevier Science. All rights reserved.     

The synthesis and reaction kinetics of some Co(IIl) and Cr(III) chloro complexes of 1,4,8-Triazaoctane (2,3-tri) and the isolation of chiral trans-dichloro [CoCl2(NH3)(2,3-tri)] ClO4

The reaction of 2,3-tri with CrCl₃·6H₂O₁, dehydrated in boiling DMF, results in the formation of mer-CrCl₃(2,3-tri) and anation of hydrolysed solutions of mer-MCl₃(2,3,-tri) (M=Co, Cr) with 6 M HCl containing HClO₄, forms trans-dichloro- mer-[MCl₂(2,3-tri)(OH₂)]ClO₄·H₂O (M=Cr, Co; I, II). trans-Dinitro-mer-[Co(NO₂)₂(NH₃)(2,3-tri)] ClO₄ crystallises from the reaction between mer-Co(NO₂)₃(2,3-tri) and aqueous 7 M ammonia, on addition of NaClO₄·H₂O, and trans-dichloro-mer-[CoCl₂(NH₃)(2,3-tri)]ClO₄ (III) can be isolated by treatment of the dinitro with 12 M HCl. Reaction of mer-CoCl₃(2,3-tri) with C₂O₄₂⁻, followed by addition of aqueous NH₃ and NaClO₄·H₂O results in the isolation of racemic mer-[Co(ox)(NH₃)(2,3-tri)]ClO₄· H₂O. This complex was resolved into its enantiomeric forms and treatment of these with SOCl₂/MeOH/ HClO₄ gave the chiral forms of trans-dichloro-mer- [CoCl₂(NH₃)(2,3-tri)]ClO₄ (R or S at the see-NH center). The rates of loss of the first chloro ligand from these dichloro complexes have been measured spectrophotometrically in 0.1 M HNO₃ over a 15 K temperature range to give the following kinetic parameters; (I) k_H(298)=7.25 × 10⁻⁵ s⁻¹, E_a=78.5 kJ mol⁻¹, δS₂₉₈^#=₋69 J K⁻¹ mol⁻¹; (II) k_H(298)=4.00 × 10⁻³ s⁻¹, E_a=89.9, δS₂₉₈^#= +87.5; (III) k_H(298)=3.09 × 10⁻⁴ s⁻¹, E_a=103, δS₂₉₈^#=+27. Treatment of the dichloro cations with Hg²⁺/HNO₃ results in the generation of mer- M(2,3-tri)(OH₂)₃³⁺ (M=Cr, Co; IV, V) and trans- diaqua-mer-Co(NH₃)(2,3-tri)(OH₂)₂³⁺ (VI). The Co(III) cations isomerise to the fac configuration with (V) K_isom(298) μ=1.0 M)=2.97 × 10⁻⁵ s⁻¹, E_a=115, δS₂₉₈^#=+46. (VI) K_isom(298) (μ=1.0 M)=4.13 × 10⁻⁵ s⁻¹, E_a=113, δS₂₉₈^#=+52.     

Biotechnological application of homo- and heterotrinuclear iron(III) furoates for cultivation of iron-enriched Spirulina

New trinuclear iron(III) furoates with the general formula [Fe₃O(α-fur)₆(R-OH)₃]X, where α-fur C₄H₃OCOO, R = CH₃ (1), C₂H₅ (2), n-C₃H₇ (3), n-C₄H₉ (4), X = NO₃⁻ (1-4); [Fe₃O(α-Fur)₆(DMF)(CH₃OH)₂]NO₃ (5); [Fe₃O(α-Fur)₆(H₂O)(CH₃OH)₂]Cl (6); [Fe₂MO(α-Fur)₆(L)(H₂O)₂], where L = THF (7-9), DMF (10-12), M = Mn²⁺ (7, 10), Co²⁺ (8, 11), Ni²⁺ (9, 12) and [Fe₂MO(α-Fur)₆(3Cl-Py)₃], where M = Mn²⁺ (13), Co²⁺ (14), Ni²⁺ (15); have been prepared and investigated by Mössbauer and IR spectroscopy. The X-ray crystal structure for the 1·2CH₃OH complex indicates that it crystallizes in the monoclinic crystal system (P2₁/n) and has a structure typical of μ₃-O-bridged trinuclear iron(III) compounds. Coordination compounds 1, 4, 7, 8 can be used as regulators of the biochemical composition of cyanobacterium Spirulina platensis biomass. The supplementation of these compounds, in concentrations exceeding 5-10 mg/l, increases the content of iron, amino acids, peptides and carbohydrates in Spirulina.     

DFT and docking studies of rhodostreptomycins A and B and their interactions with solvated/nonsolvated Mg2+ and Ca2+ ions

The interactions of L-aminoglucosidic stereoisomers such as rhodostreptomycins A (Rho A) and B (Rho B) with cations (Mg²⁺, Ca²⁺, and H⁺) were studied by a quantum mechanical method that utilized DFT with B3LYP/6-311G**. Docking studies were also carried out in order to explore the surface recognition properties of L-aminoglucoside with respect to Mg²⁺ and Ca²⁺ ions under solvated and nonsolvated conditions. Although both of the stereoisomers possess similar physicochemical/antibiotic properties against Helicobacter pylori, the thermochemical values for these complexes showed that its high affinity for Mg²⁺ cations caused the hydration of Rho B. According to the results of the calculations, for Rho A–Ca²⁺(H₂O)₆, ΔH = ?72.21 kcal?mol^?1; for Rho B–Ca²⁺(H₂O)₆, ΔH = ?72.53 kcal?mol^?1; for Rho A–Mg²⁺(H₂O)₆, ΔH = ?72.99  kcal?mol^?1 and for Rho B–Mg²⁺(H₂O)₆, ΔH = ?95.00  kcal?mol^?1, confirming that Rho B binds most strongly with hydrated Mg²⁺, considering the energy associated with this binding process. This result suggests that Rho B forms a more stable complex than its isomer does with magnesium ion. Docking results show that both of these rhodostreptomycin molecules bind to solvated Ca²⁺ or Mg²⁺ through hydrogen bonding. Finally, Rho B is more stable than Rho A when protonation occurs.

Solution and solid state behavior of Co2+, Ni2+ and Zn2+ tosylaminoacidate systems: Crystal and molecular structure of bis(N-tosylglycinato)tetraaquocobalt(II) and bis(N-tosyl-β-alaninato)tetraaquozinc(II) complexes

The interactions between N-tosylamino acids and cobalt(II), nickel(II) and zinc(II) ions in aqueous solution and in the solid state have been investigated. From concentrated aqueous solutions, compounds of general formula [M(II)(N-tosylaminoacidato)₂(H₂O)₄](M = Co(II), Ni(II) and N-tosylaminoacidato = N-tosylglycinate (Tsgly^?), N-tosyl-α- and -β-alaninate (Ts-α- and Ts-β-ala^?); M = Zn(II) and N-tosylaminoacidate = Tsgly^?, Ts-β-ala^?) and [Zn(II)(N- tosylaminoacidato)₂(H₂O)₂] were isolated and characterized by means of thermogravimetric, electronic and infrared spectra. For two of them: [Co(Tsgly)₂(H₂O)₄](I) and [Zn(Ts-β-ala)₂(H₂O)₄](II) the crystal and molecular structures were also determined. Both compounds crystallize in the monoclinic space group P2₁/c, with two formula units in a cell of dimensions: a = 13.007(6), b = 5.036(2), c = 18.925(7) Å, β = 102.33(3)° for (I) and a = 14.173(6), b = 5.469(2), c = 17.701(7) Å, β = 106.63(3)° for (II). The structures were solved by the heavy-atom method and refined by least-squares calculations to R = 0.031 and 0.064 for (I) and (II) respectively. The cobalt and zinc atoms lie in the centers of symmetry, each bonded to two amino- acid molecules through a carboxylic oxygen atom and four water molecules in a slightly tetragonally distorted octahedral geometry. The second carboxylic oxygen atom is not involved in metal coordination. Electronic and X ray-powder spectra suggest that the tetrahydrate complexes of Co²⁺, Ni²⁺ and Zn²⁺ ions of the same amino acids are isomorphous and isostructural. No coordinative interactions between ligand and metal ions were found in aqueous solution on varying the pH values before hydroxide precipitation.     

Tyrosinase inhibitory effects of 1,3-diphenylpropanes from Broussonetia kazinoki

Six 1,3-diphenylpropanes exhibiting inhibitory activities against both the monophenolase and diphenolase actions of tyrosinase were isolated from the methanol (95%) extract of Broussonetia kazinoki. These compounds, 1–6, were identified as kazinol C (1), D (2), F (3), broussonin C (4), kazinol S (5) and kazinol T (6). The latter two species (5 and 6) emerged to be new 1,3-diphenylpropanes which we fully spectroscopically characterized. The IC₅₀ values of compounds (1, 3–5) for monophenolase inhibition were determined to range between 0.43 and 17.9 μM. Compounds 1 and 3–5 also inhibited diphenolase significantly with IC₅₀ values of 22.8, 1.7, 0.57, and 26.9 μM, respectively. All four active tyrosinase inhibitors (1, 3–5) were competitive inhibitors. Interestigly they all mainfested simple reversible slow-binding inhibition against diphenolase. The most potent inhibitor, compound 4 diplayed the following kinetic parameters k₃ = 0.0993 μM^?1 min^?1, k₄ = 0.0048 min^-1, and K_i^app = 0.0485 μM.     

Bioactive oleanane-type saponins from the rhizomes of Anemone taipaiensis

Investigation of the n-BuOH extract of the rhizomes of Anemone taipaiensis led to the isolation of five new oleanane-type triterpenoid saponins (1–5), together with seven known saponins (6–12). Their structures were determined by the extensive use of ¹D and ²D NMR experiments along with ESIMS analyses and acid hydrolysis. The aglycone of 1, 2 and 4 was determined as siaresinolic acid, which was reported in this genus for the first time. The cytotoxicities of the saponins 1–12, prosapogenins 4a, 5a, 10a–12a and sapogenins siaresinolic acid (SA), oleanolic acid (OA), hederagenin (HE) were evaluated against five human cancer cell lines, including HepG2, HL-60, A549, HeLa and U87MG. The monodesmosidic saponins 6–8, 5a, 10a–12a and sapogenins SA, OA, HE exhibited cytotoxic activity toward all cancer cell lines, with IC₅₀ values ranging from 2.25 to 57.28 μM. Remarkably, the bisdesmosidic saponins 1–4 and 9 showed selective cytotoxicity against the U87MG cells.     

Ansamycin derivatives from the marine-derived Streptomyces sp. SCSGAA 0027 and their cytotoxic and antiviral activities

Fourteen ansamycin derivatives including seven new herbimycins G–L (1–6) and divergolide O (7), and seven known analogues were isolated from a culture broth of the marine-derived Streptomyces sp. SCSGAA 0027. Their complete structures were determined by detailed analysis of spectroscopic data and quantum chemical calculations. Compounds 1–5 and 7 featured an additional eight-membered O-heterocycle that has rarely been reported for ansamycins, and the Z,Z- and E,E-configurations for Δ²,Δ⁴ were reported for the first time in geldanamycin analogues. Compound 1 exhibited weak inhibition activity towards Hsp90α with an IC₅₀ value of 96 µM, 2–5 showed mild cytotoxicity against four human cancer cell lines with IC₅₀ values ranging from 13 μM to 86 μM, and 7 had moderate anti-HSV-1 activity with an IC₅₀ value of 19 µM and very weak cytotoxicity towards Vero cell. The possible biosynthetic pathways for 1–5 were proposed. And their structure-bioactivity relationship was also discussed.     

Synthesis and properties of some O-[2,2-bis(alkylthio)ethyl]-glycolaldehydes

O-[2,2-Bis(alkylthio)ethyl]glycoaldehydes (1a–e; alkyl = Et, Pr, Prⁱ, Bu^t, and -CH₂-, respectively) have been prepared from the corresponding O-[2,2-bis(alkylthio)ethyl]glycolaldehyde dimethyl acetals (2a–e) by acid hydrolysis. In anhydrous 1,4-dioxane in the presence of BF₃ · (Et₂O)₂,1a–c were partially transformed into glycolaldehyde bis(dialkyl dithioacetals),1d afforded trans-2,6-bis(tert-butylthio)-1,4-dioxane and 3,5-bis(tert-butylthio)-1,4-oxathiane, and1e did not react. The acetals2a–e) were prepared from the appropriate glycolaldehyde dialkyl dithioacetal by O-alkylation with bromoacetaldehyde dimethyl acetal.