Tris silane with sulfone

Optimization of the previously reported Mannich-type reaction of trimethyl (pent-2-en-3-yloxy)silane with the sulfone Is derived from phenyl acetaldehyde (Table 5, entry 11) led to the corresponding (3-amino ketone in a good yield with moderate diastereoselectivity (2 mol% Bi(0Tf)3-4H20, yield = 84%, 24v/24v syn/anti = 72 28) (Scheme 8). Reduction of the major diastereoisomer 24v with lithium tri-ferf-butoxyaluminohydride afforded 25 as the only one diastereoisomer. Further cyclization of the latter with NaH afforded 4-benzyl-6-ethyl-5-methyl-l,3-oxazinan-2-one 26. The relative configuration of the six-membered carbamate was established as cis-cis by NMR analysis. 

Treatment of. E-vinyl sulfonates 340 with tris(trimethylsilyl)silane and triethylborane provides a diastereoselective route to yy -2,6-tetrahydropyans 341 in high yield (Equation 145) <2000JOG4523>. 

In the simplest application of this concept, Chatgilialoglu and Curran carried out allylation reactions with allyl phenyl sulfones in the presence of tris(trimethylsilyl)-silane [58]. These reactions are analogous to the tin-mediated reactions previously discussed however, tris(trimethylsilyl)silane is used instead of tributyltin hydride or hexabutylditin for propagating the radical chain. The yields in these reactions ranged from moderate to good. 

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