PhSiH . reduction with

The 6-deoxy- -L-altropyranose derivative (48) was obtained by stereoselective hydrosilylation (Me PhSiH -[Rh(norbornadien)Cl]2) of the 5,6 ene (49) followed by protodesilylation (Bu iNF). The stereocontrol led synthesis of 3-deoxy-l,2-0-isopropylidene-8-L-threo-pentofuranose (50) from diacetoneqlucose involved reduction of the known enal (51) first with sodium borohydride then with nickel boride. Only moderate stereoselectivity was attained in the reduction [with LiAlH, ... 

The reaction of PhSiHs with the Ni-Me precursors has been shown to resnlt in the formation of ohgosilanes (PhSiH) . The initial step of this reaction is beheved to go throngh a concerted a-bond metathesis (Kh/Kd 10), bnt mnltiple intermediates are formed in the later stages of the catalysis, some of which result from the reductive elimination see Reductive Elimination) of the indenyl ligand (Scheme 8). ... 

Isayama described the coupling reaction of J -methyUmine 157 and ethyl crotonate catalyzed by Co(acac)2 and mediated by PhSiHs to produce Man-nich product 158 in 82% with syn-selectivity (Scheme 41) [71]. The b-lactam 159 was readily synthesized by heating 158. In 2002, Matsuda et al. reported cationic Rh complex [Rh(COD) P(OPh)3 2]OTf (1 mol%) as an active catalyst for the reductive Mannich reaction [72]. N-Tosylaldimine 160 was coupled with methyl acrylate and Et2MeSiH (200 mol%) at 45 °C to give the b-amino ester 161 in 96% with moderate anfi-selectivity 68%. 

A similar approach, a representative case being shown below, has led to high enantioselectivities in conjugate reductions of vinylic benzoxazoles, benzothiazoles, and related heteroaromatics e.g., vinylpyridines). JOSIPHOS analog 173, together with PhSiHs in toluene assisted by t-BuOH, afforded high yields of P-alkylated adducts. 

A number of alkylation products from MeOTf and heterocycles have been advocated as useful intermediates. Thus treatment of 2-substituted thiazoles with MeOTf in acetonitrile, followed by reduction of the salt formed with sodium borohydride/CuO in CH2CI2, leads to aldehydes. l-(Benzenesulfonyl)-3-methylimidazolium and l-(/>-toluenesulfonyl)-3-inethylimidaz-olium triflates have been proposed as efficient reagents for the preparation of aryl sulfonamides and aryl sulfonates. MeOTf alkylates 2,5-oxazoles to give salts which can be reduced by PhSiHs/CsP to give 4-oxazolines, and these provide a route to stabilized azomethine ylides. ... 

The V0(0Et)Cl2-catalyzed reaction of styrenes with molecular oxygen in the presence of a co-reductant such as PhSiHs results in oxidation-reduction and oxidative bond cleavage of styrenes (Scheme 2.42) [99]. Coordination of the A -heterocyclic multidentate ligand, the 2,6-pyridinedicarboxantide of histamine (BIPA), increases the relative yield of the latter product. The Mn(OAc)2-catalyzed oxidation of a-methylstyrene in the presence of BIPA under molecular oxygen selectively leads to 2-phenyl-2-propanol via oxidation-reduction. BIPA is also useful as a ligand in the Mn(OAc)2-catalyzed epoxidation of a-methylstyrene with PhlO. 

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