An Et3SiH-promoted diastereoselective reductive aldol reaction has been developed using InBr3 as a catalyst. This three-component reaction afforded only silyl aldolates as products without any side reactions.
I. Shibata, H. Kato, T. Ishida, M. Yasuda, A. Baba, Angew. Chem. Int. Ed., 2004, 43, 711-714.
An efficient methodology for the reductive alkylation of secondary amines with aldehydes and Et3SiH using an iridium complex as a catalyst has been developed. In addition, a cheaper, easy-to-handle, and environmentally friendly reducing reagent such as polymethylhydrosiloxane (PMHS) in place of Et3SiH was also useful.
T. Mizuta, S. Sakaguchi, Y. Ishii, J. Org. Chem., 2005, 70, 2195-2199.
Reductive amination of aldehydes and ketones with the InCl3/Et3SiH/MeOH system is highly chemoselective and can be applied to various cyclic, acyclic, aromatic, and aliphatic amines. Functionalities including ester, hydroxyl, carboxylic acid, and olefin are tolerated.
O.-Y. Lee, K.-L. Law, C.-Y. Ho, D. Yang, J. Org. Chem., 2008, 73, 8829-8837.
Facile reductive etherification of carbonyl compounds can be conveniently performed by reaction with triethylsilane and alkoxytrimethylsilane catalyzed by iron(III) chloride. The corresponding alkyl ethers, including benzyl and allyl ethers, of the reduced alcohols were obtained in good to excellent yields under mild reaction conditions.
K. Iwanami, H. Seo, Y. Tobita, T. Oriyama, Synthesis, 2005, 183-186.
A novel one-pot procedure for a directly reductive conversion of esters to the corresponding ethers by Et3SiH in the presence of a catalytic amount of InBr3 is described. This simple catalytic system appeared to be remarkably tolerant to several functional groups.
N. Sakai, T. Moriya, T. Konakahara, J. Org. Chem., 2007, 72, 5920-5922.
Various silyl ethers were readily and efficiently transformed into the corresponding alkyl ethers in high yields by the use of aldehydes combined with triethylsilane in the presence of a catalytic amount of iron(III) chloride.
K. Iwanami, K. Yano, T. Oriyama, Synthesis, 2005, 2669-2672.
A chemoselective activation of a secondary amide with triflic anhydride in the presence of 2-fluoropyridine enables a mild reduction using triethylsilane, a cheap and rather inert reagent. Imines can be isolated after a basic workup or readily transformed to the aldehydes following an acidic workup. The amine moiety can be accessed by addition of Hantzsch ester to the reaction mixture.
G. Pelletier, W. S. Bechara, A. B. Charette, J. Am. Chem. Soc., 2010, 132, 12817-12819.
A palladium-catalyzed reduction of 2-pyridinyl esters using hydrosilanes is applicable to the preparation of aliphatic, aromatic, and α,β-unsaturated aldehydes. Various functional groups, such as fluoro, methoxy, aldehyde, acetal, and ester, are tolerated.
J. Nakanishi, H. Tatamidani, Y. Fukumoto, N. Chatani, Synlett, 2006, 869-872.
Optimizations to generate CuH in situ have led to an efficient and inexpensive hydrosilylation method for dialkyl ketones.
B. H. Lipshutz, C. C. Caires, P. Kuipers, W. Chrisman, Org. Lett., 2003, 5, 3085-3088.
A regioselective reductive ring opening of benzylidene acetals in carbohydrate derivatives using triethylsilane and molecular iodine is fast and compatible with most of the functional groups encountered in oligosaccharide synthesis, and offers excellent yields. The reaction conditions are equally effective in thioglycosides.
R. Panchadhayee, A. K. Misra, Synlett, 2010, 1193-1196.
Aliphatic carboxyl derivatives (acids, acyl chlorides, esters) and aldehydes were efficiently reduced to the methyl group by HSiEt3 in the presence of catalytic amounts of B(C6F5)3. Aromatic carboxylic acids, as well as other carbonyl functional equivalents, underwent smooth partial reduction to the corresponding TES-protected benzylic alcohols in competition with a Friedel-Crafts-like alkylation decreasing the overall selectivity of the reduction process.
V. Gevorgyan, M. Rubin, J.-X. Liu, Y. Yamamoto, J. Org. Chem, 2000, 66, 1672-1675.
In situ generation of molecular hydrogen by addition of triethylsilane to palladium on charcoal results in rapid and efficient reduction of multiple bonds, azides, imines, and nitro groups, as well as deprotection of benzyl and allyl groups under mild, neutral conditions.
P. K. Mandal, J. S. McMurray, J. Org. Chem., 2007, 72, 6599-6601.
A new procedure for catalytic reductive coupling of aldehydes and alkynes uses Ni(COD)2 with an imidazolium carbene ligand as the catalyst and triethylsilane as the reducing agent.
G. M. Mahandru, G. Liu, J. Montgomery, J. Am. Chem. Soc., 2004, 126, 3698-3699.
A three-component nickel-catalyzed coupling of enals, alkynes, and silanes forms an enol silane and a trisubstituted alkene with >98:2 stereoselectivity. The reaction tolerates a broad range of functionality including aldehydes, ketones, esters, free hydroxyls, and basic secondary amines.
A. Herath, J. Montgomery, J. Am. Chem. Soc., 2008, 130, 8132-8133.
The use of a catalytic amount of PtCl2 enables the conversion of α-hydroxypropargylsilanes to (Z)-silylenones through a highly selective silicon migration via alkyne activation. The complementary (E)-silylenones are accessed by a regioselective hydrosilylation of the ynone precursor.
D. A. Rooke, E. M. Ferreira, J. Am. Chem. Soc., 2010, 132, 11926-11928.
Indium hydride (Cl2InH) was generated by the transmetalation of InCl3 with Et3SiH. In the previously reported system (NaBH4-InCl3), the coexistent borane can cause side reactions. The use of Et3SiH instead of NaBH4 affords effective hydroindation of alkynes. N. Hayashi, I. Shibata, A. Baba, Org. Lett., 2004, 6, 4981-4983.
Palladium-catalyzed reduction of aromatic nitro groups to amines can be accomplished in high yield, with wide functional group tolerance and short reaction times at r.t. using aqueous potassium fluoride and polymethylhydrosiloxane (PMHS) for aromatic nitro groups. Aliphatic nitro compounds are reduced to the corresponding hydroxylamines using triethylsilane instead of PMHS/KF.
R. J. Rahaim, R. E. Maleczka (Jr.), Org. Lett., 2005, 7, 5087-5090.
Organic azides are easily and chemoselectively reduced to the corresponding amines by reaction with dichloroindium hydride under very mild conditions. γ-Azidonitriles give pyrrolidin-2-imines in an outstanding cyclization.
L. Benati, G. Bencivenni, R. Leardini, D. Nanni, M. Minozzi, P. Spagnolo, R. Scialpi, G. Zanardi, Org. Lett., 2006, 8, 2499-2502.
Reduction of ethanethiol esters of α-amino acids to α-amino aldehydes by triethylsilane and catalytic palladium-on-carbon is described. α-Amino aldehydes with Boc, Cbz, or Fmoc protection could be obtained without racemization in high yield.
H. Tokuyama, S. Yokoshima, S.-C. Lin, L. Li, T. Fukuyama, Synthesis, 2002, 1121-1123.