The Enantioselective Birch−Cope Sequence for the Synthesis of Carbocyclic Quaternary Stereocenters. Application to the Synthesis of (+)-Mesembrine
作者:Tapas Paul、William P. Malachowski、Jisun Lee
DOI:10.1021/ol0615228
日期:2006.8.1
A synthetic technique for generating carbocyclic quaternary stereocenters with exceptionally high levels of enantioselectivity is described. A sequence of three reactions, enantioselective Birch reduction-allylation, enol ether hydrolysis, and Cope rearrangement, is used to stereoselectively generate chiral quaternary centers on a 2-cyclohexen-1-one ring. The products of the sequence are 4,4-disub
Exploration of the Enantioselective Birch−Cope Sequence for the Synthesis of Carbocyclic Quaternary Stereocenters
作者:Tapas Paul、William P. Malachowski、Jisun Lee
DOI:10.1021/jo0621423
日期:2007.2.1
2-cyclohexen-1-one ring are synthesized with good to excellent levels of enantioselectivity. The quaternary stereocenter is created through a new synthetic sequence involving three reactions: the enantioselective Birch reduction-allylation, enol ether hydrolysis, and the Cope rearrangement. To illustrate the ability of the sequence to enantioselectively generate complex structures, a variety of substrates are described
Ring A of taxol was synthesized from the bromodiene 5 and acryloyl chloride to give 6, which was resolved by separation of diastereomers 7. Allylic oxidation of 7 gave 8, which on deprotection, esterification and reduction gave 11. Heating 11 followed by reduction and protection gave 13. The C-ring component was made using asymmetric Birch reduction methodology combined with standard functional group
An efficient approach to bridged-bicyclic rings via intramolecular diazo ketone insertion
作者:Lei Chen、Xuqing Zhang、Arthur Schultz
DOI:10.1016/s0040-4039(02)00878-x
日期:2002.5
A regioselective intramoleculardiazoketone insertion reaction of chiral cyclohexenones is described. The methodology shows potential utility in the syntheses of bicyclo[4.2.1]nonan-9-one, bicyclo[4.3.1]decan-10-one and cyclooctanoid rings.