Acylation proton sponges

An interesting bifunctional system with a combination of In(OTf)3 and benzoyl-quinine 65 was developed in p-lactam formation reaction from ketenes and an imino ester by Lectka [Eq. (13.40)]. High diastrereo- and enantioselectivity as well as high chemical yield were produced with the bifunctional catalysis. In the absence of the Lewis acid, polymerization of the acid chloride and imino ester occurred, and product yield was moderate. It was proposed that quinine activates ketenes (generated from acyl chloride in the presence of proton sponge) as a nucleophile to generate an enolate, while indium activates the imino ester, which favors the desired addition reaction (66) ... 

The acylate anion from Mn(CO)3(j/-C5H5) and LiMe reacts similarly reaction with l,8-bis(dimethylamino)naphthalene (proton sponge) affords the vinylidene, although in this reaction, it is the binuclear complex which is isolated as the final product (38) ... 

Proton sponges with A-aryl and A-acyl groups. 944... 

All known proton sponge analogues of this type contain /V-phenyl, /V-acyl, /V-amino or /V-niii oso groups. Though the majority of these compounds is not characterized by increased basicity, consideration of their structural and physicochemical features gives additional insight into the peri-interaction of the amino groups. 

Proton sponges with N-aryl and N-acyl groups... 

Proton sponge analogues with /V-acyl substituents are commonly prepared by treatment of l-dimethylamino-8-methylaminonaphthalene (6) with the corresponding carboxylic acid anhydride, as in the case of 8543, or with acyl chloride, as for 86 and 8766. 

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