Allylamines hydrogen migration

Olefinic double-bond isomerization is probably one of the most commonly observed and well-studied reactions that uses transition metals as catalysts [1]. However, prior to our first achievement of asymmetric isomerization of allylamine by optically active Co(I) complex catalysts [2], there were only a few examples of catalytic asymmetric isomerization, and these were characterized by very low asymmetric induction (<4% ee) [3], In 1978 we reported that an enantioselective hydrogen migration of a prochiral allylamine such as AVV-diethylgerany-lamine, (1) or N V-diethylnerylamine (2) gave optically active citronellal ( )-enamine 3 with about 32% ee utilizing Co(I)-DIOP [DIOP = 2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino)butane] complexes as the catalyst (eq 3.1). 

Enantioselective isomerization of olefins for preparation of optically active olefins has great synthetic potential with a long tradition [1] and the non-stereoselective version is probably the most intensively investigated reaction in transition metal catalysis [2]. In particular, stereoselective hydrogen migration in a-functionalized olefins, for example allyl alcohols and allylamines [3], affording optically active aldehydes, ketones and amines, is part of the standard repertoire of enantioselec-... 

S. Otsuka, K. Tani, Catalytic Asymmetric Hydrogen Migration of Allylamines, Synthesis 1991, 665-680. 

An enantioselective hydrogen migration of prochiral allylamines 188 and 190 to chiral enamines 189 was realized by use of chiral cobalt catalysts300 (equation 18). 

A further highlight was introduced by R. Noyori in the 1980s when an efficient stereoselective hydrogen migration (allylamine —> enamine) was found to occur with Rh catalysts containing the BINAP diphosphine ligand of axial chirality (see Scheme 3 and Section 2.9). An L-menthol synthesis with an annual production of 2000 tons was the first commercial result of this development at Takasago Perfumery Co. Ltd. in Japan [66]. 

Rhodium(I) Catalyzed Enantioselective Hydrogen Migration of Prochiral Allylamines... 

---