On the basis of the observation that (E)-1-bromo-1-alkenes undergo preferentially stereospecific Pd-catalyzed cross-couplings with a variety of organometallics, in the presence of the corresponding (Z)-stereoisomers, efficient and convenient diastereoselective procedures have been developed to prep. nearly stereoisomerically pure (E)-1-trimethylsilyl-2-alkenes, (E)-1-trimethylsilyl-1-alken-3-ynes (I), (1E, 5E)-1-trimethylsilyl-1,5-alkadien-3-ynes (II), and (1E,3E)-1-trimethylsilyl-1,3-alkadienes (III) from stereoisomeric mixts. of alkenyl bromides. Compds. I have been stereoselectively converted into (1E,3Z)-1-trimethylsilyl-1,3-dienes (IV) by selective hydrometallations, followed by hydrolysis. Some synthetic applications of compds. I-IV have been also examd.
Palladium-catalyzed diastereoselective syntheses of (E)-1-trimethylsilyl-2-alkenes, (E)-1-trimethylsilyl-1-alken-3-ynes, (1E,5E)-1-trimethylsilyl-1,5-alkadien-3-ynes, (1E,3Z)- and (1E,3E)-1-trimethylsilyl-1,3-alkadienes
CARPITA, ADRIANO;ROSSI, RENZO;
1989-01-01
Abstract
On the basis of the observation that (E)-1-bromo-1-alkenes undergo preferentially stereospecific Pd-catalyzed cross-couplings with a variety of organometallics, in the presence of the corresponding (Z)-stereoisomers, efficient and convenient diastereoselective procedures have been developed to prep. nearly stereoisomerically pure (E)-1-trimethylsilyl-2-alkenes, (E)-1-trimethylsilyl-1-alken-3-ynes (I), (1E, 5E)-1-trimethylsilyl-1,5-alkadien-3-ynes (II), and (1E,3E)-1-trimethylsilyl-1,3-alkadienes (III) from stereoisomeric mixts. of alkenyl bromides. Compds. I have been stereoselectively converted into (1E,3Z)-1-trimethylsilyl-1,3-dienes (IV) by selective hydrometallations, followed by hydrolysis. Some synthetic applications of compds. I-IV have been also examd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
