An efficient enzymatic preparation of (+)- and (−)-conduritol E, a cyclitol with C2 symmetry
摘要:
Lypozyme(R) IM (immobilised lipase from Mucor miehei) catalyses the enantiomeric alcoholysis of tetraacetylconduritol E (+/-)-2 to give enantiopure (1R,2R,3R,4R)-tetrahydroxycyclohex-5-ene (-)-1, and the unreacted ester (1S,2S,3S,4S)-tetraacetyloxycyclohex-5-ene, (+)-2. The latter was transformed by basic hydrolysis into (+)-1 in high yield and 95% ee. Selective amination of partial ester (-)-3, obtained by short alcoholysis of (+/-)-2, furnished the previously unreported conduramine F-4, (-)-4. (C) 1997 Published by Elsevier Science Ltd.
作者:Timothy J. Donohoe、Peter R. Moore、Michael J. Waring、Nicholas J. Newcombe
DOI:10.1016/s0040-4039(97)01061-7
日期:1997.7
The preparation and dihydroxylation of a series of polyenes and cyclicallylicalcohols using the TMEDA/osmium tetroxide mixture is reported. Remarkably, these reagents lead to high levels of regiochemical and stereochemical control as the oxidant hydrogen-bonds to the allylicalcohol group. A mechanistic hypothesis is presented which invokes the formation of a reactive, bidentate complex between osmium
Directed Dihydroxylation of Cyclic Allylic Alcohols and Trichloroacetamides Using OsO<sub>4</sub>/TMEDA
作者:Timothy J. Donohoe、Kevin Blades、Peter R. Moore、Michael J. Waring、Jon J. G. Winter、Madeleine Helliwell、Nicholas J. Newcombe、Geoffrey Stemp
DOI:10.1021/jo026161y
日期:2002.11.1
The oxidation of a range of cyclicallylicalcohols and amides with OsO4/TMEDA is presented. Under these conditions, hydrogen bonding control leads to the (contrasteric) formation of the syn isomer in almost every example that was examined. Evidence for the bidentate binding of TMEDA to OsO4 is presented and a plausible mechanism described.
Efficient Synthesis of Enantiopure Conduritols by Ring-Closing Metathesis
作者:Morten Jørgensen、Erik H. Iversen、Andreas L. Paulsen、Robert Madsen
DOI:10.1021/jo0101297
日期:2001.6.1
to enantiopure conduritols are described starting from the chiral pool. In both cases, the cyclohexene ring is assembled via ring-closing olefin metathesis. The terminal diene precursers for the metathesis reaction are prepared either from octitols or from tartaric acids. The former route involves a new method for selective bromination of the primary positions in long-chain carbohydrate polyols. Subsequent
A diastereocontrolled route to conduritols A-F has been developed starting from a commonchiralbuildingblock containing an oxabicyclo[3.2.1]octane framework.
Six possible diastereomers of conduritols have been synthesized diastereoselectively in an integrated manner starting from a single chiral precursor, which served as a synthetic equivalent of chiral cis-1,4-dihydroxycyclohexa-2,5-diene.