Synthesis of bicyclic N-pyrrolylboranes via hydroboration of 2-vinyl and 2-allylpyrrole
作者:Bernd Wrackmeyer、Bernd Schwarze
DOI:10.1016/s0022-328x(96)06921-5
日期:1997.4
The hydroboration of 2-vinyl and 2-allylpyrrole with various hydroborating agents [Et2BH2BEt2, (9-BBN)2, (CH2)4BH2B(CH2)4, thex(H)BH2B(H)thex, Az-BH2—THF (Az = pyrrole, 2,5-dimethylpyrrole, indole), Et2O-BH2Cl, Me3Si(H)NB2H5] leads in most cases finally to B-substituted bicyclic N-pyrrolylboranes 8–11, 15–20. In the case of the reaction with tetraalkyldiboranes(6), stable intramolecular 2-H-pyrrole-borane
2-乙烯基和2-烯丙基吡咯与各种硼氢化剂[Et 2 BH 2 BEt 2,(9-BBN)2,(CH 2)4 BH 2 B(CH 2)4,thex(H)BH 2 B的硼氢化(H)thex,Az-BH 2 -THF(Az =吡咯,2,5-二甲基吡咯,吲哚),Et 2 O-BH 2 Cl,Me 3 Si(H)NB 2 H 5 ]在大多数情况下最终导致乙氨基取代二环式的N- pyrrolylboranes 8-11,15-20。与tetraalkyldiboranes反应(6)的情况下,稳定的分子内2-H吡咯-硼烷加合物6,7,12-14首先形成,其在的情况下6,12和13,可以转换成双环的N- pyrrolylboranes 8,15和16分别。尽管双环N-吡咯基硼烷中的空间条件是有利的,但11 B,13 C和14 N NMR数据不支持硼原子与杂芳族吡咯体系之间的任何显着π相互作用。