An expedient route for the practical synthesis of pachastrissamine (jaspine B) starting from 3,4,6-tri-O-benzyl-d-galactal

A practically efficient stereoselective synthesis of pachastrissamine (jaspine B) is described starting from 3,4,6-tri-O-benzyl-d-galactal in eight steps and 11% overall yield.

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(2S,3S,4S,5R)-1,2-O-Isopropylidine-3,6-anhydro-4-O-benzyl-5-O-methane-sulfonyl-d-galactitolC17H24O7SDe >99%[α]D = +12.0 (c 0.050, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S,4S,5R)

(2S,3S,4S,5S)-1,2-O-Isopropylidine-3,6-anhydro-4-O-benzyl-5-azido-d-galactitolC14H21O4N3De >99%[α]D = +47.8 (c 0.138, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S,4S,5S)