Paper
Reactivity of (R)-4-phenyloxazolidin-2-thione chiral auxiliary: from deprotection to heterocyclic interconversion
Published Oct 1, 2008 · J. Monbaliu, B. Tinant, J. Marchand‐Brynaert
Heterocycles
3
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Influential Citations
Abstract
Using (R)-3-beilzyl-4-phenyloxazolidin-2-thione (2) as model compound, a sequence of reactions has been established that allows the chiral auxiliary deprotection to furnish a primary amine. Treatment of 2 with ethyl triflate (3b) followed by ring opening with RbI (4b) and HI elimination with DBU, in a one pot process, gave S-ethyl-N-benzyl-N-1-phenylvinylcarbamothioate (5, 95% yield) which acid hydrolysis (9) and saponification liberated benzylamine. Through a mechanistic study, we showed that the activated chiral oxazolidin-2-thione 3b is a tunable intermediate towards the corresponding oxazolidin-2-one 7, thiazolidin-2-one 8 and thiazolidin-2-thione 10. All those reactions were chemoselective and preserved the chiral center. A structural analysis of this series of heterocycles, by NMR and X-ray diffraction, has been performed.
The chiral auxiliary (R)-4-phenyloxazolidin-2-thione can be deprotected to furnish a primary amine, which can then be converted into a series of heterocycles with chemoselective reactions and preserving the chiral center.
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