Preparation of 2,4-Disubstituted Cyclopentenones by Enantioselective Iridium-Catalyzed Allylic Alkylation: Synthesis of 2′-Methylcarbovir and<i>TEI-9826</i>
作者:Pierre Dübon、Mathias Schelwies、Günter Helmchen
DOI:10.1002/chem.200800495
日期:2008.7.28
A broadly applicable synthesis of chiral 2- or 2,4-substituted cyclopent-2-enones has been developed by combining asymmetric iridium-catalyzedallylic alkylation reactions and ruthenium-catalyzed ring-closing metathesis. Enantiomeric excesses (ee values) in the range of 95-99 % ee have been achieved. This method offers a straightforward access to biologically active prostaglandins of the PGA type.
<i>O</i>-Monoacyltartaric Acid Catalyzed Enantioselective Conjugate Addition of a Boronic Acid to Dienones: Application to the Synthesis of Optically Active Cyclopentenones
作者:Masaharu Sugiura、Ryo Kinoshita、Makoto Nakajima
DOI:10.1021/ol502526y
日期:2014.10.3
Enantioselective conjugateaddition of styrylboronic acid to dienones was effectively catalyzed by an O-monoacyltartaric acid to afford monostyrylated products with good enantioselectivity. The RCM of the monostyrylated products using the Hoveyda–Grubbs II catalyst afforded optically active cyclopentenones, including a synthetic intermediate of the antitumor agent TEI-9826. The study shows that a diene
The synthesis of both enantiomers of TEI-9826 has been accomplished in seven steps with an overall yield of 44% starting from diastereomeric camphor protected 3-[(dimethoxyphosphoryl)methyl]-4,5-dihydroxycyclopent-2-enones. The key steps include a fully diastereoselective hydrogenation of the endocyclic carbon-carbon double bond in the cyclopentenone ring controlled with a chiral diol moiety and the conversion of the latter into a new transposed olefinic bond. (C) 2010 Elsevier Ltd. All rights reserved.