Using Nucleophilic Substitution Reactions to Understand How a Remote Alkyl or Alkoxy Substituent Influences the Conformation of Eight-Membered Ring Oxocarbenium Ions
作者:Stephen Chamberland、K. A. Woerpel
DOI:10.1021/ol047998d
日期:2004.12.1
[reaction: see text] A remote alkoxy substituent strongly stabilizes one particular conformer of an eight-membered ring oxocarbenium ion by a through-space electrostatic effect. X-ray crystallographic analysis of a crystalline derivative proves that kinetically controlled nucleophilic substitution favors the 1,4-trans product. Nucleophilic substitution of the corresponding alkyl-substituted acetate
induction in the iodocarbocyclizationreaction of 4-pentenylmalonate derivatives having a stereogenic center at an allylic or a homoallylic position has been investigated. The iodocarbocyclizationreactions of 3-oxy-4-pentenylmalonate derivatives proceeded with high cis-selectivity through stereoelectronic control of the oxygenated substituent at an allylic position. In the reaction of (S)-2-siloxy-4-pentenylmalonate
A ring closing metathesis-osmylation approach to oxygenated oxepanes as carbohydrate surrogates
作者:Jerome C.Y. Wong、Patrick Lacombe、Claudio F. Sturino
DOI:10.1016/s0040-4039(99)01881-x
日期:1999.12
A ring closing metathesis (RCM)-osmylation sequence has been developed for the formation of highly oxygenated cyclic ethers from the corresponding acyclic dienes. A systematic examination of various substrates in this reaction revealed that the process is general in scope and is insensitive to the number of alkoxy substituents present. Subsequent osmylation of the metathesis product proceeds with excellent diastereoselectivity to furnish highly oxygenated oxepanes. These oxepanes represent one-carbon homologated carbohydrates. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
REITZ, ALLEN B.;NORTEY, SAMUEL O.;MARYANOFF, BRUCE E.;LIOTTA, DENNIS;MONA+, J. ORG. CHEM., 52,(1987) N 19, 4191-4202
作者:REITZ, ALLEN B.、NORTEY, SAMUEL O.、MARYANOFF, BRUCE E.、LIOTTA, DENNIS、MONA+
DOI:——
日期:——
KIM, YOUNG GYU;CHA, JIN K., TETRAHEDRON LETT., 29,(1988) N 17, 2011-2014