Details

Autor(en) / Beteiligte

• Garzan, Atefeh
• Jaganathan, Arvind
• Salehi Marzijarani, Nastaran
• Yousefi, Roozbeh
• Whitehead, Daniel C.
• Jackson, James E.
• Borhan, Babak

Titel

Solvent-Dependent Enantiodivergence in the Chlorocyclization of Unsaturated Carbamates

Ist Teil von

• Chemistry : a European journal, 2013-07, Vol.19 (27), p.9015-9021

Ort / Verlag

Weinheim: WILEY-VCH Verlag

Erscheinungsjahr

2013

Quelle

Wiley InterScience Journals

Beschreibungen/Notizen

• A remarkable solvent‐controlled enantiodivergence is seen in the hydroquinidine 1,4‐phthalazinediyl diether ((DHQD)2PHAL)‐catalyzed chlorocyclization of unsaturated carbamates. Eyring plot analyses of this previously unreported reaction are used to probe and compare the R‐ and S‐selective pathways. In the CHCl3/hexanes solvent system, the pro‐R process shows a surprising increase in selectivity with increasing temperature. These studies point to a strongly solvent‐dependent entropy–enthalpy balance between the pro‐R and pro‐S pathways. Two solvents, two enantiomers: Enantiodivergent hydroquinidine 1,4‐phthalazinediyl diether ((DHQD)2PHAL)‐catalyzed chlorocyclization of unsaturated carbamates, controlled solely by the choice of solvent, yields oxazolidinones in high enantioselectivity (see scheme; DCDMH=1,3‐dichloro‐5,5‐dimethyl hydantoin). The origin of the observed enantiodivergence is traced back to a solvent‐selected entropy–enthalpy balance between pro‐R and pro‐S pathways that dictates the course of the reaction.