Pandits total synthesis of -castanospermine

H (v) 50% aq. KOH, AIIBr, CH2C 2. cat Bu4NI, HO— (vii) Dess-Martin periodinane, 

Earlier work2e by Miller and Chamberlin had already shown that borane-dimethyl sulfide was the reagent of choice for deoxygenating the amide of 13. The final step of the synthesis was O-debenzylation by catalytic hydrogenation. Note how the addition of acid helped prevent the catalyst from getting poisoned by the amine, ensuring that deprotection was rapid and efficient. 

Pandit s synthesis of (+ )-castanospermine stands out for its seminal demonstration of the applicability of the Grubbs RCM reaction5 to dienes containing one electrophilic alkene and one nucleophilic alkene. When considered alongside Crowe and Goldberg s landmark work on the cross-metathesis of electron-deficient alkenes,6 Pandit s synthesis has 

This maximises overlap of the developing nitrogen lone pair with the lactam carbonyl.10 

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