Umpolung-Carbonyl SynthonsPolarity inversion is an old concept, but vigorous research in the area is of relatively recent origin.The concept of synthons, or functional group equivalents, has spurred research.Synthons: structural units within a molecule which are related to possible synthetic operationsCorey Pure Appl. Chem 1967 191. homoenolates2. α-electrophiles3. acyl anionsROROO
NH2RONROPt(III)2H2OROPt(III)2RNROORHPtH3NOH2NOONO2PtH3NNHH2NNHONO2t-But-BuRORONα-ElectrophilesMatsumoto et al. JACS ASAP2+++• π-coordination of triple bond to the Pt(III) atom• nucleophilic attack of water• ketonyl–Pt(III) complexes react with amines to give α-amino substituted ketone• with 1° amines, further reaction occursH
AcylAnions2. Thiazolium salt catalyzed additioncat. thiazolium salt,Et3N, DMF• in the presence of base, quaternary thiazolium salts are converted to the ylide, which acts as catalyst (5-10 mol %)• aliphatic, aromatic, and heterocyclic aldehydes add to α,β-unsaturated ketones, esters, and nitriles• Et3N or NaOAc are preferred bases• DMF, dioxane, or even alcohols can function as solventSNHONNNH2Clvitamin B1 (thiamine)SNHOClSNHOBrSNHOIOHR+OXOROX
NH2RONROPt(III)2H2OROPt(III)2RNROORHPtH3NOH2NOONO2PtH3NNHH2NNHONO2t-But-BuRORONα-ElectrophilesMatsumoto et al. JACS ASAP2+++• π-coordination of triple bond to the Pt(III) atom• nucleophilic attack of water• ketonyl–Pt(III) complexes react with amines to give α-amino substituted ketone• with 1° amines, further reaction occursH
AcylAnions2. Thiazolium salt catalyzed additioncat. thiazolium salt,Et3N, DMF• in the presence of base, quaternary thiazolium salts are converted to the ylide, which acts as catalyst (5-10 mol %)• aliphatic, aromatic, and heterocyclic aldehydes add to α,β-unsaturated ketones, esters, and nitriles• Et3N or NaOAc are preferred bases• DMF, dioxane, or even alcohols can function as solventSNHONNNH2Clvitamin B1 (thiamine)SNHOClSNHOBrSNHOIOHR+OXOROX
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