Resolution of 1‐n‐Butyl‐3‐Methyl‐3‐Phospholene 1‐Oxide With TADDOL Derivatives and Calcium Salts of O,O'‐Dibenzoyl‐(2R,3R)‐ or O,O'‐di‐p‐Toluoyl‐(2R,3R)‐tartaric Acid

The resolution methods applying (?)‐(4R,5R)‐4,5‐bis(diphenylhydroxymethyl)‐2,2‐dimethyldioxolane (“TADDOL”), (?)‐(2R,3R)‐α,α,α',α'‐tetraphenyl‐1,4‐dioxaspiro[4.5]decan‐2,3‐dimethanol (“spiro‐TADDOL”), as well as the acidic and neutral Ca²⁺ salts of (?)‐O,O'‐dibenzoyl‐ and (?)‐O,O'‐di‐p‐toluoyl‐(2R,3R)‐tartaric acid were extended for the preparation of 1‐n‐butyl‐3‐methyl‐3‐phospholene 1‐oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single‐crystal X‐ray analysis. The absolute P‐configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra. Chirality 26:174–182, 2014. © 2014 Wiley Periodicals, Inc.     

Molecular tweezers for enantiodiscrimination in NMR: Di‐(R,R)‐1‐[10‐(1‐hydroxy‐2,2,2‐trifluoroethyl)‐9‐anthryl]‐2,2,2‐trifluoroethyl benzenedicarboxylates

A series of new chiral molecular tweezers, di‐(R,R)‐1‐[10‐(1‐hydroxy‐2,2,2‐trifluoroethyl)‐9‐anthryl]‐2,2,2‐trifluoroethyl phthalate (2), isophthalate (3) and terephthalate (4), were synthesized and their structure studied by NMR and molecular mechanics. Their effectiveness as chiral solvating agents for the determination of the enantiomeric purity of chiral compounds using NMR was demonstrated. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

Claisen–Schmidt condensation: Synthesis of (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives with different substituents in H2O/EtOH

A simple, green, and direct three‐component condensation of acetophenone, aromatic aldehydes with 3‐oxo‐N‐phenylbutanamide (acetoacetanilide) to generate some novel (1S,6R)/(1R,6S)‐2‐oxo‐N,4,6‐triarylcyclohex‐3‐enecarboxamide derivatives was carried out over K₂CO₃ (10 mol%) with high efficiency in water/ethanol as green solvent at room temperature. This protocol proceeded via Claisen–Schmidt condensation and Michael addition. The present methodology offers several advantages, such as short reaction time, high yield, more readily available and inexpensive materials, more environmentally friendly, no need for column chromatography, simple work‐up procedure, and the absence of volatile and hazardous organic solvents.