Asymmetric Cyclopentannelation. Chiral Auxiliary on the Allene
作者:Paul E. Harrington、Marcus A. Tius
DOI:10.1021/ol0001362
日期:2000.8.1
An enantioselective variant of the synthesis of cross-conjugated cyclopentenones, based on D-glucose-derived chiral auxiliaries, is described. Minor modification of the method makes it applicable to the preparation of both enantiomeric series of products. Both enantiomers of the key intermediate in our roseophilin synthesis have been prepared.
A Formal Total Synthesis of Roseophilin: Cyclopentannelation Approach to the Macrocyclic Core
作者:Paul E. Harrington、Marcus A. Tius
DOI:10.1021/ol990124k
日期:1999.8.1
[formula: see text] The formaltotalsynthesis of the macrocyclic core of roseophilin 4 has been accomplished in 12 steps from 5-hexenal 8. The cyclopentannelation reaction was used to form the aliphatic five-membered ring of 3. Diene 2 was assembled by means of a Stetter reaction. Ring-closing metathesis of 2, reduction, and Knorr reaction of the 1,4-diketone 5 gave the ketopyrrole 3.
作者:Paul E. Harrington、Tsuyoshi Murai、Chester Chu、Marcus A. Tius
DOI:10.1021/ja020591o
日期:2002.8.1
The scope of an enantioselective cyclopentannelation reaction that makes use of allenyl ether-derived nucleophiles has been probed. The enantioselectivity is induced by a traceless chiral auxiliary that is easily derived from camphor. It has been shown that for gamma-substituted allene ethers that are axially chiral, very high enantiomeric excesses of cyclopentenone products are observed in the matched cases. Two fundamentally different mechanisms are observed, one for the cyclizations of allenyl ketones (see eq 7), the other for the cyclizations of allenyl alcohols (see eq 11). The methodology is versatile, efficient, and well-suited for applications in synthesis.