Acylsilanes review

Recently, analogues of nucleosides [60], natural products Huperzine-A [61] and Hydroartemisinin [62], and inhibitors of metallo-/ -lactamases have been synthesised [63]. With acylsilane electrophiles, the initial adducts undergo Brook rearrangement which is interrupted by -Si bond fission with loss of fluoride anion (Eq. 16), leading to the formation of extremely useful difluoro-enol silanes [64]. Of the various fluoride sources employed, the tetrabutylam-monium triphenyldifluorostannate described by Gingras appears to be particularly effective. The numerous other methods for trifluoromethylation formed the subject of an exhaustive review [65]. More recently, the Olah group described a chlorodifluoromethyl trimethylsilane which is expected to have a rich chemistry [66]. 

Bulman Page, P.C., Klair, S.S., and Rosenthal, S. (1990). Synthesis and chemistry of acylsilanes. Chemical Society Reviews, 19, 147-195. 

Acylsilanes, compounds in which a carbonyl group is directly attached to a silicon atom, have been much investigated using photochemical methods. The chemistry of acylsilanes has been reviewed94 and an excellent review and discussion of all the details of acylsilane photolysis has recently been published1. 

Review. Cirillo and Panck1 have reviewed progress in the chemistry of these compounds during the last two to three years (48 references). A new synthesis involves homologation of aldehydes with methoxybis(trimcthylsilyl)methyllithium (l)2 to form cnol ethers of an acylsilanc (equation I). Acylsilanes can be prepared in high yield by... 

A short review in Japanese of the photochemistry of organosilicon compounds including acylsilanes has been published. Sensitization and quenching experiments show that the triplet state of acetyltrimethylsilane is involved in reaction (11). " Furthermore, as the lifetime of the triplet state (t 13 ns) does not vary... 

The displacement of primary iodides in some carbohydrate derivatives by lithiated 2-trimethylsilyl-l,3-dithiane followed by hydrolysis of the dithioacetal has allowed the synthesis of some acylsilanes (e.g. 21 from 20), and a review on the oxidation of the carbon-silicon bond has included a number of carbohydrate examples. ... 

Numerous methods are available for the preparation of acylsilanes and have been adequately covered in reviews. Hence, procedures potentially applicable for a large-scale preparation are briefly described here. 

Startg. chiral acylsilane treated with 2 eqs. -BuLi in THF at —78° for 5 min intermediate hydroxysilane (Y 92% diastereomer ratio > 100 1), treated with BU4NF in DMF at room temp. 5yn-product. Overall Y 89% (diastereomer ratio > 100 1). The diastereomer ratio is noticeably lower (5 1) by direct reaction from the corresponding aldehyde. F.e. inch reaction with allyltrimethylsilane (in the presence of TiCy and with allylmagnesium bromide s. M. Nakada et al., J. Am. Chem. Soc. 110, 4826-7 (1988) review of synthesis and synthetic potential of acylsilanes s. A. Ricci, A. DeglTnnocenti, Synthesis 1989, 647-60 review of the steric influence of the trimethylsilyl group s. J.R. Hwu, N. Wang, Chem. Rev. 89, 1599-615 (1989). 

As described in more detail in an earlier review simple acylsilanes, RsSiCOR, undergo two types of reaction when photolyzed. One involves the rapid reversible 1,2-silyl shift from carbon to oxygen of the carbonyl group leading to a siloxycarbene which can... 

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