Stereoselective Synthesis of (+)--Conhydrine from R-(+)-Glyceraldehyde

Scheme 3

Reagent and conditions: (a) Boc₂O, Et₃N, DMAP, DCM, 0°C to rt, 5 h, 79%; (b) PTSA, MeOH, rt, 12 h, 88%; (c) TsCl, Bu₂SnO, Et₃N, DCM, 0°C to rt, 5 h, 64%; (d) (i) K₂CO₃, MeOH, 0°C, 1 h, 90%; (ii) MeMgI, THF, 0°C, 2 h, 76%; (e) Grubbs’ catalyst I gen., DCM, rt, 8 h, 89%; (f) 10% Pd/C, H₂, MeOH, rt, 10 h, 90%; (g) TFA, DCM, 0°C to rt, 4 h, 64%.