Indolyl-3-methanamine

Fig. 9.9 Transformation of the phytoalexin brassinin (28) by (i) L. maculans virulent on canola to indole-3-carboxaldehyde (30) and (ii) L. maculans virulent on brown mustard to indolyl-3-methanamine (31)...

The 3-indolyl methanamine structural motif 503 is embedded in numerous indole alkaloids and synthetic indole derivatives . An efficient catalytic asymmetric Friedel-Crafts reaction of indoles 501 with imines 502 provides a direct, convergent, and versatile method for the highly enantioselective construction of 3-indolyl methanamines 503 from readily accessible achiral precursors (Scheme 101) <2006JA8156 and references therein>. 

The AFC reaction of indoles with less reaetive aryl aldimines catalyzed by organocatalystwas reported by the group of Deng in 2006. Bifunctional cinchona alkaloid-derived thioureas were utilized to promote the AFC reaetion of indoles with N-Ts- or AT-Bs-protected imines. With 10 mol% of eatalyst 29, 3-indolyl methanamine derivatives 30 were obtained in high yields with up to 97% ee for both aryl and alkyl imines (Scheme 6.12). 

Scheme 6.19 One-pot procedure for enantioselective synthesis of 2-indolyl methanamine derivatives reported by You.

As shown in Scheme 10.29, You and coworkers [50] disclosed the enantioselective aza-Friedel-Crafts reaction of indoles 145 with A-sulfonyl aldimines 146 by a (5)-BINOL-derived phosphoric acid 147. Their reactions in toluene completed within several hours for most of the substrates, providing a series of 3-indolyl methanamine derivatives 148 with up to >99% ee and the opposite absolute configuration from the previously described method. Unfortunately, when... 

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