E)-2-(5-Trimethylstannyl-2-thienyl)ethenyldimethylphenylsilane, (E)-8, which can be stereospecifically prepared from (Z)-1-dimethylphenylsilyl-2-(2-thienyl)-1-trimethylstannylethene, (Z)-6, or from (E)-2-(2-thienyl)ethenyldimethylphenylsilane, (E)-9, serves as an equivalent to the 2-ethenylthiophene d1', d5-synthon, 20, in an efficient two-step synthesis of 5-ethenyl-5'-(1-propynyl)-2,2'-bithiophene, 10, a naturally-occurring photoxin. In the first step of this synthesis compound (E)-8 undergoes a palladium-catalyzed cross-coupling reaction with 2-iodo-5-(1-propynyl)thiophene, 16, and in the second step the so obtained cross-coupling product, (E)-17, undergoes a protodesilylation reaction.
Synthetic applications of stereodefined 2-substituted 1-silyl-1-stannylethenes: a new synthesis of 5-ethenyl-5'-(1-propynyl)-2,2'-bithiophene, a naturally-occurring phototoxin
ROSSI, RENZO;CARPITA, ADRIANO;
1991-01-01
Abstract
E)-2-(5-Trimethylstannyl-2-thienyl)ethenyldimethylphenylsilane, (E)-8, which can be stereospecifically prepared from (Z)-1-dimethylphenylsilyl-2-(2-thienyl)-1-trimethylstannylethene, (Z)-6, or from (E)-2-(2-thienyl)ethenyldimethylphenylsilane, (E)-9, serves as an equivalent to the 2-ethenylthiophene d1', d5-synthon, 20, in an efficient two-step synthesis of 5-ethenyl-5'-(1-propynyl)-2,2'-bithiophene, 10, a naturally-occurring photoxin. In the first step of this synthesis compound (E)-8 undergoes a palladium-catalyzed cross-coupling reaction with 2-iodo-5-(1-propynyl)thiophene, 16, and in the second step the so obtained cross-coupling product, (E)-17, undergoes a protodesilylation reaction.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
