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DOI: 10.1055/s-2008-1078009
Chiral Spiroborate-Catalyzed Borane Reduction of Ketoxime Ethers
Contributor(s):Hisashi Yamamoto, Pingfan LiUniversity of Puerto Rico-Humacao, Puerto Rico
Highly Enantioselective Borane Reduction of Heteroaryl and Heterocyclic Ketoxime Ethers Catalyzed by Novel Spiroborate Ester Derived from Diphenylvalinol: Application to the Synthesis of Nicotine Analogues
J. Org. Chem. 2008, 73: 4017-4026
Publication History
Publication Date:
22 August 2008 (online)
Key words
borane reduction - ketoxime ethers - spiroborate esters
Significance
This work provides a good method for the preparation of various chiral amines. The previous difficulties in using oxime ether as substrates are solved through the adoption of a spiroborate ester as catalyst. The high chemical yields and enantiomeric excesses obtained are very attractive for future applications.
Comment
Expansion of substrate scope for this spiroborate ester catalyzed reaction shows that it could be at least comparable with the traditional oxazaborolidine catalyst for these related reductions, if not better than those. In the case of the reported nicotine analogue synthesis, however, it would be even better if a multi-gram scale entry is shown for this transformation.