Borabenzene Derivatives. 23.<sup>1</sup> New Synthetic Entry into Borabenzene Chemistry via Doubly Kaliated Pentadienes: Synthesis of 1-(Dimethylamino)-3-methylene-1,2,3,6-tetrahydroborinines and Lithium 1-(Dimethylamino)boratabenzene Derivatives
作者:Gerhard E. Herberich、Ulli Englert、Martin U. Schmidt、Regina Standt
DOI:10.1021/om960031w
日期:1996.6.11
as (E)-2-methyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, and 2-tert-butyl-4-methyl-1,3-pentadiene react with BCl2(NMe2) to form 1-(dimethylamino)-3-methylene-1,2,3,6-tetrahydroborinines 3a (5-R = H), 3b (5-R = Me), and 3c (5-R = But) in moderate yields. The compounds 3a−c dimerize reversibly to give crystalline dimers (3a)2, (3b)2, and (3c)2 as C2v and C2h isomers. The structure of C2v-(3a)2 was
从合适的二烯1(例如(E)-2-甲基-1,3-戊二烯,2,4-二甲基-1,3-戊二烯和2-叔丁基-4-甲基-1,3 )进行二碱化反应而获得的二氨基甲酸酯。-戊二烯与BCl 2(NMe 2)反应形成1-(二甲基氨基)-3-亚甲基-1,2,3,6-四氢硼烷3a(5-R = H),3b(5-R = Me)和3c(5-R = Bu t),产量中等。化合物3a-c可逆地二聚,得到结晶二聚体(3a)2,(3b)2和(3c)2为C2 v和C 2 h异构体。通过X射线衍射确定C 2 v-(3a)2的结构。在溶液中建立了一个单体/二聚体平衡,其中K = 49.0 mol L -1以便在22.0°C时解离,ΔH =(70±2)kJ mol -1,ΔS =(270±8)JK -1 mol -1。亚甲基-1,2,3,6-四氢硼烷酮3在100-120°C时发生热异构化,生成二氢硼烷酮。因此3b提供了3,5-二甲基-