Reaction of Aminodihydropentalenes with HB(C6F5)2: The Crucial Role of Dihydrogen Elimination
摘要:
The aminodihydropentalene derivative la reacts with the Lewis acidic RB(C6F5)(2) boranes (2a-c) by C-C bond cleavage to yield the formal borylene insertion products 3. In contrast, 1a,b react with HB(C6F5)(2) at 55 degrees C by elimination of dihydrogen to yield the iminium-stabilized zwitterionic heterofulvenes 10a,b. The reaction pathways were studied by preparation of the kinetically controlled intermediates 7a,b and the thermodynamically controlled products 9a,b, monitored by variable-temperature NMR experiments, and supported by DFT calculations. The trapping reactions of 9a with HCl and PhCHO, respectively, led to the addition products 13 and 14. Compounds 3c, 7a,b, 10a,b, 11, 13, and 14 were characterized by X-ray diffraction.
Make and break: Stronglyelectrophilicboranes RB(C6F5)2 (R=Me, CH2CH2Ph) react with an aminodihydropentalene substrate by CC bondcleavage with concomitant borylene insertion to yield the ring‐enlarged zwitterionic borate/iminium product.
产生和破坏:强亲电子的硼烷RB(C 6 F 5)2(R = Me,CH 2 CH 2 Ph)通过CC键断裂与伴随的亚芳基插入而与氨基二氢戊烯底物反应生成环扩大的两性离子硼酸酯/亚胺盐产品。