The Chemistry of Substituted Norbornenes. Reactions of 5-Vinyl-2-norbornene and 5-Ethylidene-2-norbornene with Formic Acid
作者:Yoshiharu Inoue、Fumio Tanimoto、Hisao Kitano
DOI:10.1246/bcsj.57.2468
日期:1984.9
Addition of formic acid to 5-vinyl-2-norbornene(1) and subsequent hydrolysis afford 6-vinyl-exo-2-norbornanol(5) and 5-vinyl-exo-2-norbornanol(6). Similarly, from 5-ethylidene-2-norbornene(2) are formed 6-ethylidene-exo-2-norbornanol(14), 5-ethylidene-exo-2-norbornanol(15), and 6-ethyltricyclo[2.2.1.02,6]heptan-3-ol(16). The hydroboration of 2 also leads to the formation of 14 and 15. Thus, the vinyl- and ethylidene-exo-norbornanols, 5, 6, 14, and 15, and the corresponding endo-norbornanols, 9, 10, 21, and 22, have been synthesized. A structural analysis of these products by 13C NMR revealed that under certain conditions, the ethylidene group of 2 exerts a great influence upon the reactivity of the norbornenyl ring double bond. Moreover, the fact that 16 derived from the addition of formic acid to 2 consists of both exo- and endo-hydroxy epimers is inconsistent with the previous observations that the exo-isomer is generally the sole product in related systems.
将甲酸添加至5-乙烯基-2-诺尔苯烯(1)后,经过水解可得6-乙烯基-exo-2-诺尔醇(5)和5-乙烯基-exo-2-诺尔醇(6)。类似地,从5-乙基烯基-2-诺尔苯烯(2)中可形成6-乙基烯基-exo-2-诺尔醇(14)、5-乙基烯基-exo-2-诺尔醇(15)和6-乙基三环[2.2.1.0²,⁶]庚-3-醇(16)。2的氢硼化也会导致形成14和15。因此,乙烯基和乙基烯基-exo-诺尔醇5、6、14和15,以及相应的内诺尔醇9、10、21和22已被合成。通过13C NMR对这些产物的结构分析表明,在某些条件下,2的乙基烯基对诺尔苯烯环双键的反应性产生了很大的影响。此外,由于16是由甲酸与2反应生成的,包含了ex-d和endo-羟基对映体,这与以前观察到的ex-isomer通常是相关体系中唯一产物的现象不一致。