| Indoles, when treated with methyldiazomalonate under catalysis by rhodium(II)acetate, undergo C-H and N-H insertion reactions regioselectively depending on the substitution pattern on the indole moiety. In indoles where the 3-position is unsubstituted, high yields of the C3-H insertion product were observed. In 3-alkylindoles, 2-substitution predominated, while N -methyltetrahydrocarbazole yielded the product resulting from insertion into the C6-H bond. Indoles in which the nitrogen is unprotected yield varying degrees of N-H insertion.;Syntheses of the Aspidosperma alkaloids Aspidospermidine and Quebrachamine have been investigated. Our initial approaches towards these compounds involved ring closing metathesis (RCM), intramolecular Heck cross-coupling reaction, cycloannulation of cyclopropane tethered to an indole, novel homo [3+2] cycloadditions of nitrone and cyclopropanediesters, and exhaustive hydrogenation. The latest and most promising route to these alkaloids involved an elegant cascade reactions initiated by Staudinger reaction. A single Staudinger reaction was performed and proved unsuccessful. Due to time constraint, optimization of this reaction was not possible. This result placed our synthetic effort two steps away from Quebrachamine, and with few slight modifications, this route can be employed towards the syntheses of Aspidospermidine and Goniomitine. |
