Asymmetric cyclopentannelation: camphor-derived auxiliary.
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.
Harrington
Paul E
PE
Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu 96822, USA.
Murai
Tsuyoshi
T
Chu
Chester
C
Tius
Marcus A
MA
D000498:Allyl Compounds / Q000138:chemical synthesis; D002164:Camphor / Q000031:analogs & derivatives*; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000498:Allyl Compounds; D003517:Cyclopentanes; D002164:Camphor; C013905:cyclopentenone