The reactions of aryl-stabilized sulfur ylides with organoboranes has been studied under a variety of conditions. At 5 or -78 degrees C, the reaction with Et3B gave a mixture of the first and second homologation products, but at -100 degrees C, only the first homologation product was obtained even with just 1.1 equiv of Et3B. Under these optimized conditions, the chiral sulfur ylides (derived from camphor sulfonic acid) with different aryl groups were reacted with Et3B to give the corresponding alcohols (95-98% yield, 96-98% ee) and amines (74-77% yield, >98% ee). The origin of the high enantioselectivity is discussed. The use of nonsymmetrical 9-BBN derivatives was also explored. It was found that whereas primary alkyl substituents gave mixtures of products derived from competing migration of the boron substituent and the boracycle, all other groups resulted in either exclusive migration of the boron substituent (Ph, hexenyl, i-Pr) or exclusive migration of the boracycle (hexynyl, cyclopropyl). The factors responsible for the outcome of the reactions involving a hindered (i-Pr) and an unhindered (propynyl) substituent were studied by DFT calculations. This revealed that, in the case of an unhindered substituent, the conformation of the ate complex is the dominant factor whereas, in the case of a hindered substituent, the barriers to interconversion between the conformers of the ate complex and subsequent migration control the outcome of the reaction.

A series of new thienyl ring containing analogues of nelfinavir and saquinavir with different substitution patterns were synthesized from suitable enantiopure diols. Their inhibitory activity against wild type recombinant HIV-1 protease was evaluated. In general thienyl groups spaced from the core by a methylene group gave products showing IC(50) in the nanomolar range, irrespective of the type and the substitution pattern of the heterocycle. The range of activity of the two most active compounds is substantially maintained or even increased against two commonly selected mutants, under drug pressure, such as V32I and V82A.

Amberlyst 15 is an efficient catalyst for the reaction of aryl‐substituted oxiranes with acetone to prepare 2,2‐dimethyl‐1,3‐dioxolanes in high yields. trans‐2,3‐Diaryloxiranes afford trans‐acetonides enantiospecifically at room temperature, and the use of enantiopure 2,3‐diaryloxiranes results in no loss of stereochemical integrity in the resulting trans‐acetonides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Keywords: Epoxides / Ring-opening reactions / Reduction / Alcohols / Enantioselectivity / Regioselectivity Non-symmetrical trans-2,3-diaryloxiranes have been regioselectively opened by catalytic hydrogenation over Pd/C, NaBH 4 /Pd and [Cp 2 TiCl]/H 2 O. Although in the catalytic hydrogenation reactions the epoxides were mainly opened at the β-carbon with respect to the substituted aryl ring in all cases, with the [Cp 2 TiCl]/H 2 O system the regioselectivity was affected by the electronic properties of the aryl residues, the epoxides being opened on the carbon bearing the most

New structurally simple indolic non peptidic HIV Protease inhibitors were synthesized from (S)-glycidol by regioselective methods. Following the concept of targeting the protein backbone, different substitution patterns were introduced onto the common stereodefined isopropanolamine core modifying the type of functional group on the indole, the position of the functional group on the indole and the type of the nitrogen containing group (sulfonamides or perhydroisoquinoline), alternatively. The systematic study on in vitro inhibition activity of such compounds confirmed the general beneficial effect of the 5-indolyl substituents in presence of arylsulfonamide moieties, which furnished activities in the micromolar range. Preliminary docking analysis allowed to identify several key features of the binding mode of such compounds to the protease.