Unmasked beta-substituted acrylate alpha-anion equivalents have been directly and very efficiently prepared by insertion of zinc metal into the carbon-iodine bonds of alkyl (E)- or (Z)-2-iodo-2-alkenoates, (E)- or (Z)-(4), respectively. The stereoisomeric composition of these new reagents, 12, depends on the experimental conditions used for their preparation. Their Pd0-catalyzed reaction with alkenyl or aryl halides, which can contain functional groups, leads chemoselectively to the corresponding cross-coupled products in high yields. When the reagents 12 are synthesized from compounds (Z)-4 or long reaction times are used for their preparation, their cross-coupled products result are rich in the stereoisomers with trisubstituted double bonds of (E)-configuration.
PALLADIUM-CATALYZED REACTION BETWEEN ARYL OR ALKENYL HALIDES AND (1-CARBALKOXY-1-ALKENYL)ZINC IODIDES - A NEW CLASS OF UNMASKED BETA-SUBSTITUTED ACRYLATE ALPHA-ANION EQUIVALENTS
ROSSI, RENZO;CARPITA, ADRIANO;BELLINA, FABIO;
1993-01-01
Abstract
Unmasked beta-substituted acrylate alpha-anion equivalents have been directly and very efficiently prepared by insertion of zinc metal into the carbon-iodine bonds of alkyl (E)- or (Z)-2-iodo-2-alkenoates, (E)- or (Z)-(4), respectively. The stereoisomeric composition of these new reagents, 12, depends on the experimental conditions used for their preparation. Their Pd0-catalyzed reaction with alkenyl or aryl halides, which can contain functional groups, leads chemoselectively to the corresponding cross-coupled products in high yields. When the reagents 12 are synthesized from compounds (Z)-4 or long reaction times are used for their preparation, their cross-coupled products result are rich in the stereoisomers with trisubstituted double bonds of (E)-configuration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
