The addition of alkynes to a tetrasilyldisilene Evidence for a biradical intermediate
The addition of alkynes to a tetrasilyldisilene Evidence for a biradical intermediate
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炔烃与四甲硅烷基二硅烯的加成 双自由基中间体的证据
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发表时间：
2005
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通讯作者：
K. Baines
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作者：
S. Gottschling;M. Jennings;K. Baines
研究了两种新开发的机制探针（反式，反式-2-甲氧基-3-苯基环丙基）乙烯(1)和（反式，反式-2-甲氧基-1-甲基-3-苯基环丙基）乙烯(2)与四烷基（叔丁基二甲基硅基）二烯(3)的加成反应。1与3加成得到1-[2-（顺-2-甲氧基-3-苯基环丙基）乙烯]-1,1,2,2-四（叔丁基二甲基硅基）二硅烷(5)；而在二烯上加成炔2则得到了三个立体异构体：1,1,2,2-四（叔丁基二甲基硅基）-6-甲氧基-5-甲基-7-苯基-1,2-二硅氧烷-3,4-二烯（79）和1,1,2,2-四（叔丁基二甲基硅基）-3-（反式，反式-2-甲氧基-1-甲基-3-苯基环丙基）-1,2-二硅氧烷-3-烯（10）。环七烯79的形成提供了令人信服的证据，证明炔与四硅基二烯的加成涉及到双自由基中间体的形成。关键词：二烯，炔，环加成，反应机理，机理探针。
The addition of two newly developed mechanistic probes, (trans,trans-2-methoxy-3-phenylcyclopropyl)ethyne (1) and (trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)ethyne (2), to tetrakis(tert-butyldimethylsilyl)disilene (3) has been investigated. The addition of 1 to 3 gave 1-[2-(cis-2-methoxy-3-phenylcyclopropylidene)vinyl]-1,1,2,2-tetrakis(tert-butyldimethylsilyl)disilane (5) as the major product; whereas addition of alkyne 2 to the disilene gave three stereoisomers of 1,1,2,2-tetrakis(tert-butyldimethylsilyl)-6-methoxy-5-methyl-7-phenyl-1,2-disilacyclohepta-3,4-diene (79) and 1,1,2,2- tetrakis(tert-butyldimethylsilyl)-3-(trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)-1,2-disilacy-clobut-3-ene (10) as the major products. The formation of cycloheptaallenes 79 provides convincing evidence that the addition of alkynes to tetrasilyldisilenes involves the formation of a biradical intermediate. Key words: disilene, alkyne, cycloaddition, reaction mechanism, mechanistic probe.