Developing Strategies to Utilize Unstable Diazoalkanes from N-Silyl Enamines and Organic Azide

초록

In recent research, we have developed a synthetic strategy to furnish Z-amidines from cyclic N-silyl enamines and organic azides via [3+2] cycloaddition following the rearrangement pathway. Herein, we continued using borane-catalyzed hydrosilylation conditions for conjugated nitriles to obtain linear N-silyl enamines. These linear N-silyl enamines also underwent [3+2] cycloaddition with organic azides, but triazoline intermediate occurred a different rearrangement pathway, which produced E-formamidines and diazoalkanes as co-products. Diazoalkane was an extremely unstable compound, but it was a versatile structure to furnish abandon of functional groups in organic synthesis. Under this observation, we have already developed the new conditions to convert diazoalkanes to ester and pyrazolidines under mild conditions.