Asymmetric reductive amination total synthesis

Yao et al. reported a chemo- and stereoselective asymmetric total synthesis of (-)-lannotinidine B 179 through two reductive amination in a domino fashion. Thus, the tricarbonyl compound 175 was treated with benzylamine in the presence of NaBH(OAc)3 to give 178 via 176 and 177 (Scheme 9.30) [90]. Similar reductive amination strategies have been apphed for several other natural products [22a]. 

ASYMMETRIC HYDROAMINATION AND REDUCTIVE AMINATION IN TOTAL SYNTHESIS... 

Asymmetric Total Synthesis of ( )-Deoxoproso-phylline Zhu and Jourdant reported on an asymmetric total synthesis of (—)-deoxoprosophylline 157 starting from chiral L-Af,Af-dibenzyl serine and methyl aceto-acetate by exploiting a highly diastereoselective intramolecular reductive amination. The compound 155 underwent chemoselective iV-debenzylation followed by reductive amination to afford O-benzyl deoxoprosophyl-line 156. After this step, a simple 0-debenzylation... 

SCHEME 39.46. Asymmetric total synthesis of (—)-deoxoprosophylline employing a reductive amination protocol. 

An efficient enantioselective total synthesis of (—) -cis-clavidpitic acid was reported by Park and coworkers (Scheme 12.3) [103]. The asymmetric phase-transfer catalytic alkylation of 65a with 68 was employed as the key step, producing the urmatural oi-amino acid derivative 69 for the introduction of the 5S chirality. Starting from a glycine derivative 65a, Maruoka and coworkers successfully developed a strategy for the asymmetric synthesis of cyclic amino acids having a piperidine or azepane core structure by the combination of a phase-transfer catalytic asymmetric alkylation and a subsequent diastereoselective reductive amination. This approach allows the... 

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