An Asymmetric Synthetic Approach to the A-ring of the Taxol Family of Anti-Cancer Compounds*
A synthetic route developed for the preparation of the A-ring of Taxol family of molecules is reported. By means of an intramolecular Diels-Alder reaction an asymmetric approach to this ring has been accomplished. Also, initial studies to prepare the A ring using an intramolecular Diels-Alder reaction have been successful.
Beiträge zur chemie des bors XLI. Darstellung von organylborhalogeniden
Abstract The preparation of organohaloboranes R 3− n BX n (R = CH 3 , C 2 H 5 , C 6 H 5 ; X = F, Cl, Br. I) by two convenient procedures is described. These are based on the action of boron halides on tetraorganostannanes and dialkylamino-organoboranes respectively.
Chiral synthesis of statine
Abstract Statine ( 8a ) has been obtained in high enantiomeric purity as its N-Boc-ethyl ester ( 8b ) in a chiral synthesis. The sequence involves the enantio- and erythro-selective aldol condensation of N-Boc-L-leucinal ( 5 ) with (S)-4-(1-methylethyl)-3-[(methylthio)acetyl]-2-oxazolidinone ( 1 ) via the boron enolate, followed by desulfurization and saponification in ethanol, according to the methodology of Evans.