Novel silyl migration-mediated bond-forming reactions: Applications in organic synthesis.

摘要

The development and application of novel silyl migration-mediated bond-forming reactions is described. The primary objective of this research was to develop applications in which the silyl group not only facilitated multiple bond-forming steps, but also provided opportunities for stereocontrol of the overall transformation. A subsequent objective was to further the mechanistic understanding of the Brook rearrangement and demonstrate its utility in synthetic applications. Two key transformations were explored: the silicon-mediated Baylis-Hillman reaction and silyl migration-mediated bis-functionalizations of arene complexes.; A highly efficient method for the generation of α-methylene-β-hydroxycarbonyl compounds from aryl vinyl ketones has been developed. This new methodology successfully addressed the issue of rapid head-to-tail dimerization that is encountered when aryl vinyl ketones are utilized as Baylis-Hillman substrates. Because of their utility, these novel adducts are appealing substrates for synthetic applications, including biologically important compounds.; The use of silyl migrations as a general and efficient method for achieving multiple stereoselective bond formations has also been achieved. This successful strategy provides a compelling method to access highly functionalized arene chromium tricarbonyl complexes in a single step. The general strategy involves a tandem alkylation/silyl migration/inter- or intramolecular trapping sequence. The strategy appears to possess significant potential for the asymmetric synthesis of spirocyclic ring systems, including fredericamycin A.