Fides Benfatti

Organocatalytic Asymmetric Alkylation of Aldehydes by SN1‐Type Reaction of Alcohols

Work-alcoholic! The elusive enantioselective catalytic alpha-alkylation of aldehydes, a widely sought transformation, was brought to execution by the use of alcohols capable of forming stabilized carbocations (see scheme, TFA = trifluoroacetic acid).

Catalytic stereoselective benzylic C–H functionalizations by oxidative C–H activation and organocatalysis

An organocatalytic stereoselective alpha-alkylation reaction of aldehydes based on C-H activation is presented.

Organocatalytic Stereoselective α-Alkylation of Aldehydes with Stable Carbocations

The organocatalytic stereoselective alkylation of aldehydes is carried out with the four stable carbocations 1-4 in the presence of a catalytic amount (20 mol%) of MacMillan imidazolidinones 5-6. In all reactions, lutidine was used as a base. The alkylation reactions are investigated at different temperatures with linear and branched aldehydes. In the case of carbocation tropylium fluoroborate, an interesting reversal of alkylation product configuration was observed, which is driven by entropic effects in the reaction. The absolute configuration of the products obtained is determined by chemical correlation and found to be in general agreement with the model proposed by MacMillan to justify the stereoselectivity obtained in the reactions promoted by catalysts of type 5-6.

Merging Organocatalysis with an Indium(III)‐Mediated Process: A Stereoselective α‐Alkylation of Aldehydes with Allylic Alcohols

Keywords: aldehydes ; allylic alcohols ; indium ; MacMillan catalysts ; organocatalysis ; Nucleophilic-Substitution ; 1 ; 3-Dicarbonyl Compounds ; Acids ; Benzylation ; Catalysis ; Aminocatalysis ; Activation ; Complexes ; Chemistry ; Spectra Reference EPFL-ARTICLE-150684doi:10.1002/chem.201001693View record in Web of Science Record created on 2010-08-31, modified on 2017-05-12

Stereoselective Reactions with Stabilized Carbocations

Benzylic carbocations, which are easily generated in situ from alcohols or acetates by Bronsted or Lewis acids, undergo selective facial discrimination in diastereoselective reactions (see scheme; FG=functional group). The A values are responsible for the facial selectivity. Catalytic amounts of various Lewis acids can be employed in discriminating one face of the carbocation.

Me2Zn mediated, tert-butylhydroperoxide promoted, catalytic enantioselective Reformatsky reaction with aldehydes

A practical and highly enantioselective catalytic Reformatsky reaction with aldehydes using a cheap, commercially available aminoalcohol as ligand is described.

Me2Zn as a radical source in Reformatsky-type reactions

Experimental evidence for the generation of radicals by Me(2)Zn used in Reformatsky reactions was unequivocally established with a radical trap.