RESUMO
A reductive detrifluoromethylation protocol has been developed making use of an earth-abundant alkoxide base and silicon hydride species. A variety of pyridine and quinoline substrates bearing alkyl, aryl, and amino functional groups are reduced in moderate to high yields. The reaction is chemoselective for C(sp2)-CF3 groups located at the 2-position on the pyridine ring, leaving trifluoromethyl groups located elsewhere on the molecule intact. Preliminary mechanistic studies demonstrate that the combination of silane and base generates a strongly reducing system that may transfer an electron to electron-deficient π systems.
RESUMO
Primary acyl-phosphines are scarce in the literature. Here we show that the reaction of Ph3 GePCO with the ylide Ph3 PCH2 proceeds to give the species Ph3 PCHC(O)PH(GePh3 ) 1. Deprotonation of 1 with Na[N(SiMe3 )2 ] generates the salt [Na(THF)2 ][Ph3 PCHC(O)P(GePh3 )] 2 which provides subsequent access to the bis-germanylated acylphosphine, Ph3 PCHC(O)P(GePh3 )2 3. Alternatively, treatment of 1 with HCl in dioxane affords the primary acylphosphine Ph3 PCHC(O)PH2 4. Compound 4 is a rare example of an air stable primary acyl-phosphines and the first devoid of a stabilizing heteroatom adjacent to the carbonyl fragment.
