SmI2-coupling reaction of chiral non-racemic α-bromo-α′-sulfinyl ketones with imines: synthesis of enantiomerically pure 2-methyl-3-amino-1-ol moieties

Chiral non-racemic α-bromo-α′-sulfinyl ketones were shown to react with imines in the presence of SmI2 to give the corresponding 1,3-aminoketo derivatives with good syn-diastereoselectivity. Further reduction of these adducts either with DIBAL-H only or with DIBAL-H in the presence of Yb(OTf)3 afforded syn- and anti-2-methyl-3-amino-1-ol moieties, respectively, in good yields and diastereoselectivities.

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[2S,3R,4R,(S)R]-4-(4-Bromophenyl)-1-(tert-butylsulfinyl)-3-methyl-4-(4-methylphenylsulfonamido)butan-2-yl acetateC22H30ClNO4S2De >98%[α]D20=+336 (c 0.6, acetone)Source of chirality: (R)-methyltert-butylsulphoxideAbsolute configuration: (2S,3R,4R,(S)R)

[2R,3R,4R,(S)R]-4-(4-Bromophenyl)-1-(tert-butylsulfinyl)-3-methyl-4-(4-methylphenylsulfonamido)butan-2-yl acetateC22H30BrNO4S2De >98%[α]D20=+205 (c 0.6, acetone)Source of chirality: (R)-methyltert-butylsulphoxideAbsolute configuration: (2S,3R,4R,(S)R)

[2S,3R,4R]-4-(4-Bromophenyl)-1-hydroxy-3-methyl-4-(4-methylphenylsulfonamido)butan-2-yl acetateC20H24BrNO5S[α]D20=+115 (c 0.6, acetone)Source of chirality: (R)-methyltert-butylsulphoxideAbsolute configuration: (2S,3R,4R)