5027-16-7Relevant articles and documents
TIN TETRACHLORIDE-INDUCED ?-CYCLIZATIONS OF GLYCINE CATION EQUIVALENTS TO SUBSTITUTED PIPECOLIC ACID DERIVATIVES
Esch, Peter M.,Boska, Ilona M.,Hiemstra, Henk,Boer, Richard F. de,Speckamp, W. Nico
, p. 4039 - 4062 (2007/10/02)
Cationic ?-cyclization reactions of N-(3-alkenyl)-N-(methoxycarbonyl)acetoxyglycine esters induced by tin tetrachloride in dichloromethane are described.Reactions started and quenched with water at -78 deg C mainly yield cis-4-hydroxypipecolic esters, whereas reactions quenched after warm-up to room temperature provide trans-4-chloropipecolic esters as major products.A mechanistic scheme is advanced which adequately explains these results.The essentials are a rapid cationic aza-Cope equilibrium of the incipient iminium cation, and participation of the ester moiety through formation of a relatively stable bicyclic dioxycarbenium cation as pivotal intermediate.
Ethylideneaminooxyacetic acids and esters
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, (2008/06/13)
Compounds of the formula STR1 wherein R1 is hydrogen, alkyl, cycloalkyl, phenylalkyl, alkoxyalkyl, alkoxyaryl, aryl or an agronomically acceptable cation; R2 and R3 are each independently hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted phenylalkyl, carboxy, alkoxycarbonyl or phenyl group; X is hydrogen, fluoro, bromo, chloro or iodo atom; Y is a hydrogen, fluoro, bromo, chloro, iodo, alkyl, cycloalkyl, carboxy, alkoxycarbonyl, phenylalkyl, alkenyl and alkynyl group, wherein the alkyl, cycloalkyl, phenylalkyl and phenyl group may have up to three optional substituents; and B is hydrogen, carboxy, alkoxycarbonyl, methylene (--CH2 R4) or CZZ1 Z2 group wherein R4 is an alkyl or alkenyl group and Z, Z1 and Z2 are each independently a hydrogen, fluoro, bromo, chloro or iodo atom, provided that Z, Z1, Z2, X and Y are not all hydrogens.