Asymmetric synthesis of β-dialkylamino alcohols by transfer hydrogenation of α-dialkylamino ketones

Transfer hydrogenation of representative aryl and heteroaryl dialkylaminomethyl ketones with formic acid–triethylamine, catalyzed by RuCl[(R,R)-TsDPEN](η-p-cymene), produces the corresponding β-dialkylamino alcohols, 97–99% ee, in 50–73% yields. Asymmetric synthesis of (R)-macromerine, 98% ee, the cactus Coryphantha macromeris alkaloid, is also described.

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(S)-(−)-1-(2-Benzofuryl)-2-(dimethylamino)ethanolC12H15NO2Ee = 98%[α]D20=-46.5 (c 3.20, MeOH)Source of chirality: asymmetric synthesisAbsolute configuration: (S), X-ray analysis

(S)-(−)-1-(2-Benzofuryl)-2-(morpholin-4-yl)ethanolC14H17NO3Ee = 98%[α]D20=-32.0 (c 0.85, EtOH)Source of chirality: asymmetric synthesisAbsolute configuration: (S), X-ray analysis

(R)-(−)-2-(Dimethylamino)-1-(2-naphthyl)ethanolC14H17NOEe = 98%[α]D23=-56.0 (c 1.11, MeOH)Source of chirality: asymmetric synthesisAbsolute configuration: (R), X-ray analysis