Intramolecular reaction Mukaiyama condensation

Intramolecular Mukaiyama aldol condensation. This reaction can be used to obtain six-, seven-, and eight-membered rings. Thus the reaction of the r /.v-dioxolanc la with TiCL (1-2 equiv.) gives 2a as the exclusive product. The isomeric /ran.v-dioxolane lb under similar conditions gives a I I mixture of 2a and 2b (72% yield). No cyclization products are obtained with SnCL or ZnCL. 

The majority of reported solid-phase combinatorial syntheses of the lactam core utilize a [2-i-2] cycloaddition reaction of ketenes with resin-bound imines [33-41]. A further development of the Staudinger reaction was reported by Mata and coworkers using Mukaiyama s reagent [42]. In addition, a stereoselective synthesis of chi-rally pure P-lactams has been performed as a first utilization of polymer-supported oxazolidine aldehydes [43]. Other strategies include an ester enolate-imine condensation [44], an Hg(OCOCF3)2-mediated intramolecular cydization [45], and Miller hydroxamate synthesis [46]. Because of the variability derived from the scaffold synthesis, not many attempts have been made to derivatize the resin-bound lactam template [47]. One of the most detailed descriptions of a versatile (3-lactam synthesis on a resin employed amino acids tethered as esters on Sasrin resin [48]. 

In 2013, another intramolecular hydrosilojqrlation was combined with a Mukaiyama aldol condensation by Gong et al. in an enantioselective relay catalytic cascade. This domino reaction occurred between atylacetylene silanols and glyoxylates and was induced by a combination of an achiral gold catalyst and a chiral N-triflyl phosphoramide. As shown in Scheme 7.37,... 

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