Alkylation

About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.

Asymmetric α-Alkylation of N‘-tert-Butanesulfinyl Amidines. Application to the Total Synthesis of (6R,7S)-7-Amino-7,8-dihydro-α-bisabolene

Abstract: A highly diastereoselective α-alkylation of N‘-tert-butanesulfinyl amidines has been developed along with methods for converting the alkylation products to enantiomerically enriched amines that incorporate both α- and β-stereocenters. The utility of this chemistry is further demonstrated by the first asymmetric synthesis of the antimicrobial marine natural product (6R,7S)-7-amino-7,8-dihydro-α-bisabolene.

Highly Enantioselective Friedel–Crafts Reaction of 4,7‐Dihydroindoles with β,γ‐Unsaturated α‐Keto Esters by Chiral Brønsted Acids

Abstract: A highly efficient Friedel-Crafts reaction of 4,7-dihydroindoles with β,γ-unsaturated α-keto esters by a chiral N-triflyl phosphoramide was realized, affording the 2-substituted 4,7-dihydroindoles with up to 98% ee for a wide range of substrates. The Friedel-Crafts alkylation together with a subsequent oxidation of the product with p-benzoquinone led to a 2-alkylated indole derivative in 98% ee.

A Highly Enantioselective Phosphabicyclooctane Catalyst for the Kinetic Resolution of Benzylic Alcohols

Abstract: A new class of chiral phosphines belonging to the P-aryl-2-phosphabicyclo[3.3.0]octane family (PBO) has been prepared by enantioselective synthesis starting from lactate esters and 2,2-dimethylcyclopentanone enolate 5. A selective enolate alkylation method has been developed for preparation of 9 and 10 using a chelating ester substituent in the triflate alkylating agent 11. Subsequent conversion to the PBO catalysts 2 and 39 relies on a diastereoselective cyclization from the cyclic sulfate 17 and LiPHAr to afford the more hindered endo-aryl phosphines. These phosphines function as efficient catalysts for the kinetic resolutions of aryl alkyl carbinols by benzoylation (16, 21, 22) or iso-butyroylation in the case of the less hindered aryl alkyl carbinol substrates. With o-substituted aryl alkyl carbinols, the enantioselectivities exceed 100, and s = 380 ± 10 has been demonstrated in the case of methyl mesityl carbinol. The PBO-catalyzed acylations probably involve a P-acylphosphonium carboxylate intermedi...