Rhodium carbenes are key intermediates in a range of cycloadditions and insertion reactions. Whereas Rh(II) carbenes bearing acceptor substituents are easily accessed from stabilized diazo compounds, general and safe methods for accessing donor Rh(II) carbenes are scarce. Herein, we report the first generation of donor Rh(II) carbenes by decarbenation of 7‐substituted 1,3,5‐cycloheptatrienes. This discovery unlocks an improved retro‐Buchner–cyclopropanation sequence, a Si–H insertion reaction for a broad‐scope synthesis of allylsilanes, and a new methodology for the vinylogation of aldehydes. The last strategy led to the development of an iterative synthesis of E‐polyenes, and to the total synthesis of navenones B and C.
Donor Rhodium Carbenes by Retro‐Buchner Reaction
Angew. Chem. Int. Ed. 2019, 58 (7), 2088-2092, DOI: 10.1002/anie.201813512.