•
With TFA, aliphatic ketones are reduced to secondary alcohols, whereas aromatic ketones and aldehydes are further reduced to the hydrocarbons: J. Org. Chem., 38, 2675 (1973). With BF3, both aliphatic and aromatic carbonyl groups are reduced to the hydrocarbons: J. Org. Chem., 43, 374 (1978); Synth. Commun., 24, 1999 (1994). For selective reduction of a ketone in the presence of a nitro group, see: Org. Synth. Coll., 7, 393 (1990). Reduction of ketones to methylenes also occurs in the presence of TICl4, allowing the formation of N-protected ɑ-amino acids from keto analogues without racemization: Heterocycles, 41, 17 (1995). For reduction of carbonyl groups catalyzed by B(C6F5)3, see: J. Am. Chem. Soc., 118, 9440 (1996). Reduction of aldehydes, acyl chlorides and esters to methyl groups using this catalyst has been described: J. Org. Chem., 66, 1672 (2001). The polysubstitution and rearrangement encountered with Friedel-Crafts alkylations can be circumvented by an effective one-pot technique employing AlCl3 acylation followed by in situ reduction withEt3SiH: J. Chem. Soc., Perkin 1, 1705 (1989). See also Poly(methylhydrosiloxane), L14561, as an alternative reducing agent.•
For use as a superior cation scavenger in peptide synthesis, see Triisopropylsilane, L09585.•
In combination with TFA, "ionic hydrogenation" of alkenes occurs. This can be a useful alternative to catalytic hydrogenation, since selective reduction, e.g. of the more branched double bond of a diene can be achieved. For a review of ionic hydrogenation, see: Synthesis, 633 (1974):
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Silylation of OH groups, with elimination of H2, occurs with catalysis by TBAF under very mild conditions: Tetrahedron Lett., 35, 8413 (1994); cf Chlorotriethylsilane, A15547. The use of 2-8 mol% Tris(pentafluorophenyl)borane, L18054, has been reported to be more effective than TBAF for the silylation of alcohols and phenols, with secondary and tertiary alcohols reacting faster than primary: J. Org. Chem., 64, 4887 (1999). With excess reagent, reduction of primary alcohols and ethers to methyl occurs: J. Org. Chem., 65, 6179 (2000).•
Using various Pt group catalysts, acyl halides can be reduced to aldehydes, as an alternative to the Rosenmund reduction. For examples, see: Org. Prep. Proced. Int., 12, 13 (1980). For reduction of nitriles to aldehydes, see: Triethyloxonium tetrafluoroborate, A14420. Nitroarenes can be reduced to anilines using Wilkinson's Catalyst: Synth. Commun., 26, 973 (1996).•
For reductive alkylation of indoles, see 2-Methylindole, A10764.•
In combination with indium(III) chloride and a radical initiator, generates a radical reagent, analogous to Tri-n-butyltin hydride, A13298, which effects dehalogenation of alkyl halides to alkanes and radical addition of halides to alkenes, including dehalocyclizations: Org. Lett., 6, 4981 (2004).• High-yield, selective hydrodehalogenation of alkyl and aryl halides is catalyzed by PdCl2, avoiding the skeletal rearrangements of alkyl halides sometimes observed with Lewis acid catalysts such as AlCl3: Organometallics. 15, 1508 (1996); cf: J. Org. Chem., 41, 1393 (1976).
• For trans-hydrosilylation of alkynes, catalyzed by AlCl3, see: J. Org. Chem., 61, 7354 (1996); 64, 2494 (1999).
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ɑ?-Enones are reduced selectively to saturated ketones In the presence of TFA: Synthesis, 420 (1973); or Wilkinson's catalyst (Chlorotris(triphenylphosphine)rhodium(I), 10468): Tetrahedron Lett., 5035 (1972); Organometallics, 1, 1390 (1982).• Aryl halides have been silylated using PtO2 as a catalyst, to give aryltriethylsilanes: Org. Let.., 8, 931 (2006).
• In the presence of Ti(O-i-Pr)4, phosphine oxides can be reduced to phosphines, a useful alternative to pyrophoric HSiCl3: Tetrahedron Lett., 35, 625 (1994).
易燃性 (F)
刺激性 (Xi)
