An improved route to 1,2-dideoxy-β-1-phenyl-d-ribofuranose

An efficient synthesis of the aryl nucleoside analogue 1,2-dideoxy-β-1-phenyl- -ribofuranose (1) is described. This route utilizes the addition of phenyllithium to a protected 2-deoxyribonolactone followed by reduction with triethylsilane/boron trifluoride etherate to selectively produce the β-anomer. Deprotection yields the desired aryl C-nucleoside in 27% overall yield from 2-deoxy- -ribose.     

Synthesis of 1-C-(tetra-O-acetyl-β-d-galactopyranosyl)-2,3-diiodo-1-propene and its reaction with primary amines

Iodination of 1-C-(tetra-O-acetyl-β-d-galactopyranosyl)allene affords an E/Z-mixture of 1-C-(tetra-O-acetyl-β-d-galactopyranosyl)-2,3-diiodo-1-propene. S_N2 displacement of the allylic iodide with primary amines affords an E/Z-mixture of allylic amines under a variety of conditions. Due to its experimental simplicity and low cost of reagents, this procedure may find wide use in the laboratory for functionalization of sugar allenes.     

Preparation of spray-dried wettable powder formulations of Bacillus thuringiensis-based biopesticides

Bacillus thuringiensis is the most widely used biopesticide among many methods available to control insects. To make a saleable product, B. thuringiensis must be substantially concentrated by removal of water and formulated to improve longevity, efficacy, and ease of transport of the product. B. thuringiensis subsp. aizawai culture broth as an active ingredient was mixed with various adjuvants and then spray dried. The optimum conditions for spray drying were found to be an outlet temperature of 60-85 degrees C and an inlet temperature of 120-180 degrees C. Various adjuvants had different effects on physical and biological properties of the dried product. Gelatinized tapioca starch and milk powder improved suspensibility but adversely affected wettability of the dried formulated product. Vegetable oil and Tween 20 enhanced wettability but resulted in poor suspensibility. Silica fume was used to enhance flowability because it reduced clumping and caking of the powder resulting from the addition of vegetable oil. Formulation containing 10% wt:wt B. thuringiensis, 10% wt:wt gelatinized tapioca starch, 10% wt:wt sucrose, 38% wt:wt tapioca starch, 20% wt:wt milk powder, 10% wt:wt silica fume, 2% wt:wt polyvinyl alcohol, 5% vol:vol Tween 20, 1% vol:vol refined rice bran oil, and 1% vol:vol antifoam solution was found to be optimum in terms of the physical and biological properties of the dried product. This formulation had 55% suspensibility, 24 s for wetting time, and 5.69 x 10(4) CFU/ml of LC50 value against Spodoptera exigua larvae.     

Palladium-catalyzed hydroamination of C-(tetra-O-acetyl-β-d-galactopyranosyl)allene

Both palladium(0) and palladium(II) methods for catalyzed hydroamination of C-(tetra-O-acetyl-β-d-galactopyranosyl)allene with a variety of aromatic amines have been successfully developed.     

Synthesis and properties of carboxymethylchitosan hydrogels modified with poly(ester-urethane)

Preparation and properties of carboxymethylchitosan (CMC) modified with polyurethane (PU) containing poly(ethylene adipate) (PEA) as a soft segment is described. Urethane prepolymer was first synthesized by the reaction of PEA with an excess of 1,6-hexamethylene diisocyanate (HDI) to terminate its ends with isocyanate functional groups, followed by chain extension reaction using ethylene glycol as a chain extender. Its chemical structure was characterized by ¹H NMR and FTIR, molecular weight by GPC, and thermal behavior by DSC. To prepare PU-modified CMC (CMC-PU), 1–60 wt% of PU were introduced into the CMC solution of THF:H₂O mixture (50:50 v/v) in the presence of 10 wt% of hexamethylene-1,6-di-(aminocarboxysulfonate) (HDA) to increase network density. Formation of the network structure was confirmed by investigating percent crosslinking and water swelling properties of CMC-PU compared to CMC network without PU. When percent of PU increased from 1 to 60 wt%, percent crosslinking of CMC-PU gradually increased up to 82%, whereas equilibrium water content (EWC) dropped and retained at 1000%. SEM showed microphase separation of PU (10–50 μm) thoroughly dispersed in CMC surface and in the bulk. In addition, CMC-PU exhibited a slight enhancement in toughness properties. Cytotoxicity and biocompatibility tests indicated that CMC-PU was non-toxic.     

Synthesis of a C-galactopyranosyl-linked N-substituted 1,2-ethylenediamine

A straightforward route to a C-galactopyranosyl-linked 1,2-ethylenediamine is described. The five-step synthetic procedure involves: (i) C-allenylation of d-galactopyranose pentaacetate with propargyl trimethylsilane in the presence of a Lewis acid, (ii) iodination of allenyl galactopyranosyl tetraacetate to diiodoallyl galactopyranosyl tetraacetate, (iii) displacement of the allylic iodide with N-Boc-ethylenediamine, (iv) catalytic hydrogenation of vinyl iodide to alkane, (v) deprotection of the acetyl and N-Boc-groups using acid-catalyzed hydrolysis. This method demonstrates a general method to access a new class of carbohydrate-ethylenediamine C-glycosyl chelators.     

Facile synthesis and anticancer activity of C-10 non-acetal deoxoartemisinin dimers

In this research, N-(2-aminoethyl)glycine-linked C-10 non-acetal deoxoartemisinin dimers were synthesized by using solution phase peptide synthesis approach. In addition, chemical modification of the C-10 non-acetal deoxoartemisinin monomers and dimers by adding a lysine unit to the N-terminus has been performed. The biological activities of all synthesized compounds were evaluated against the colon cancer cell line (Caco-2). The non-acetal deoxoartemisinin monomers 12a, 15a–c and dimers 13a, 16a–c were active against Caco-2 cells and more potent than dihydroartemisinin.     

Palladium-catalyzed hydroamination of C-(tetra-O-acetyl-β-d-galactopyranosyl)allene

Both palladium(0) and palladium(II) methods for catalyzed hydroamination of C-(tetra-O-acetyl-β-d-galactopyranosyl)allene with a variety of aromatic amines have been successfully developed.