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DOI: 10.1055/s-2007-968005
Pd/P(t-Bu)3: A Mild Catalyst for Selective Reduction of Alkenes under Transfer-Hydrogenation Conditions
Publikationsverlauf
Publikationsdatum:
24. Januar 2007 (online)
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Abstract
A new and efficient mild Pd/P(t-Bu)3 catalyst for selective reduction of various alkenes under transfer-hydrogenation conditions has been developed leading to the corresponding saturated derivatives in chemical yields varying from 65% to 98%.
Key words
palladium - reduction of alkenes - tri-tert-butyl phosphine - transfer hydrogenation - catalysis
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1a
Johnstone RAW.Willby AH.Entwistle ID. Chem. Rev. 1985, 85: 129 -
1b
Kovacs J.Todd TD.Reibenspies JH.Joo F.Darensbourg DJ. Organometallics 2000, 19: 3963 -
1c
Lee SH.Park YJ.Yoon CM. Tetrahedron Lett. 2000, 41: 887 -
2a
Tsuji J. Palladium Reagents and Catalysts: Innovations in Organic Synthesis John Wiley & Sons; New York: 1995. -
2b
Poli G.Giambastiani G.Heumann A. Tetrahedron 2000, 56: 5959 -
2c
Tsuji J. Transition Metal Reagents and Catalysts: Innovations in Organic Synthesis John Wiley & Sons; New York: 2000. - For reviews on hydrogen transfer reactions, see:
-
3a
Zassinovich G.Mestroni G. Chem. Rev. 1992, 92: 1051 -
3b
Brieger G.Nestrick T. Chem. Rev. 1974, 74: 567 -
3c
de Graauw CF.Peters JA.van Bekkum H.Huskens J. Synthesis 1994, 1007 -
4a
Zoran A.Sasson Y. J. Mol. Catal. 1984, 26: 321 -
4b
Cortese NA.Heck RF. J. Org. Chem. 1978, 43: 3985 -
4c
Selvam P.Sonavane SU.Mohapatra SK.Jayaram RV. Tetrahedron Lett. 2004, 45: 3071 -
5a
Baán Z.Finta Z.Keglevich G.Hermecz I. Tetrahedron Lett. 2005, 46: 6203 -
5b
Arcadi A.Bernocchi E.Cacchi S.Marinelli F. Synlett 1991, 27 -
5c
Prasad K.Jiang X.Slade JS.Clemens J.Repič O.Blacklock TJ. Adv. Synth. Catal. 2005, 347: 1769 -
5d We must also mention the work of Arterburn involving the formation of Pd-colloids species leading to an homogeneous transfer hydrogenation of various substrates:
Arterburn JB.Pannala M.Gonzaleza AM.Chamberlin RM. Tetrahedron Lett. 2000, 41: 7847 -
5e
Nevertheless, in the present study even if no evidence has been obtained for the exclusion, or no formation, of such Pd colloids, it seems that our catalytic system was totally homogeneous. Studies are now underway to determine the exact nature of the catalyst and will be reported in due course.
- 6
Brunel JM. Mini Rev. Org. Chem. 2004, 1: 249 - 7 For a review on green chemistry, see:
Anastas PT.Kirchhoff MM. Acc. Chem. Res. 2002, 35: 686 - For a discussion of atom economy, see:
-
8a
Trost BM. Acc. Chem. Res. 2002, 35: 695 -
8b
Trost BM. Science 1991, 254: 1471
References and Notes
Selective Reduction of 4-Allylanisole(1) under Transfer Hydrogen Conditions; General Procedure (Table 1, Entry 4): CAUTION: All reagents (solvent, phosphine ligand, formic acid) must be purified before use in order to obtain good conversions and reproducible results. In a two-necked round-bottomed flask placed under argon was added Pd(OAc)2 (5.4 mg, 2.4 × 10-5 mol) at 20 °C in freshly distilled anhyd THF (5 mL). To this solution, P(t-Bu)3 (20 mg, 10-4 mol; purchased from Acros) was successively added and the solution was heated to reflux for 10 min. To this mixture 4-allylanisole (1; 148 mg, 10-3 mol) and formic acid (230 mg, 5 × 10-3 mol) were added. The resulting solution was stirred for 15 min to reflux and then cooled to 20 °C for 12 h. After filtration over Celite and evaporation of the solvents, the crude residue was purified by chromatog-raphy on a silica gel column using PE-EtOAc (100:0 → 50:50) as eluent affording the expected product 2 in 95% yield.
10Kinetic experiments performed on the selective reduction of 4-allylanisole (1) under transfer-hydrogenation conditions indicate that such a reaction takes place in less than 4 h. Nevertheless, this reaction time seems to be highly substrate-dependent and we have chosen to perform all experiments for 12 h.