Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleo...Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleophilic monofluoromethylation of aldehydes regardless of the reaction conditions at-tempted(using various organic and inorganic bases).However,it was later discovered by Hu et al.that the nucleophilic monofluoromethylation could be accomplished by employing lithium hexamethyldisi-lazide(LiHMDS)as a base.Herein,we present an in-depth computational investigation into the intrigu-ing effects of reagent structure and bases on the nucleophilic monofluoromethylation of aldehydes.The computations reveal the 1,4-diazabicyclo[2.2.2]octane(DABCO)catalyzed nucleophilic monofluoromethy-lation of benzaldehyde with acyclic FBSM is a thermodynamically unfavorable process mainly due to the destabilizing O···O lone pair repulsions in FBSM product,whereas such repulsion could be largely avoided in FBDT product because of its constrained five-membered ring structure.Employing LiHMDS as a base can not only facilitate the nucleophilic monofluoromethylation via Li–O interactions but also render the monofluoromethylation of benzaldehyde with FBSM thermodynamically favored.展开更多
基金supported by the Natural Science Foundation of China(Nos.22122104,21933004 and 21702098).
文摘Although fluorobis(phenylsulfonyl)methane(FBSM)and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide(FBDT)possess similar physicochemical properties,Shibata et al.found that FBSM failed to undergo nucleophilic monofluoromethylation of aldehydes regardless of the reaction conditions at-tempted(using various organic and inorganic bases).However,it was later discovered by Hu et al.that the nucleophilic monofluoromethylation could be accomplished by employing lithium hexamethyldisi-lazide(LiHMDS)as a base.Herein,we present an in-depth computational investigation into the intrigu-ing effects of reagent structure and bases on the nucleophilic monofluoromethylation of aldehydes.The computations reveal the 1,4-diazabicyclo[2.2.2]octane(DABCO)catalyzed nucleophilic monofluoromethy-lation of benzaldehyde with acyclic FBSM is a thermodynamically unfavorable process mainly due to the destabilizing O···O lone pair repulsions in FBSM product,whereas such repulsion could be largely avoided in FBDT product because of its constrained five-membered ring structure.Employing LiHMDS as a base can not only facilitate the nucleophilic monofluoromethylation via Li–O interactions but also render the monofluoromethylation of benzaldehyde with FBSM thermodynamically favored.
