Subscribe to RSS
DOI: 10.1055/s-0029-1219926
A Multi-Task Palladium Catalyst Involved in Heck-Reduction-Cyclization Sequences for the Preparation of 4-Benzyl-1,2-dihydroisoquinolin-3-ones: An Unusual Homogeneous-Heterogeneous Sustainable Approach
Publication History
Publication Date:
10 May 2010 (online)
Abstract
A mixed homogeneous-heterogeneous catalysis that exploits a multi-task palladium catalyst has been developed for one-pot sequential Heck-reduction-cyclization (HRC) reactions leading to novel 4-benzyl-1,2-dihydroisoquinolin-3-ones. The HRC sequence requires mild conditions and allows the separation of the palladium residues under the form of an in situ generated Pd(0)/C catalyst by simple filtration. The homemade and recovered catalyst can be efficiently reused for Suzuki-Miyaura reactions and reductive processes making it useful for sustainable chemistry.
Key words
heterogeneous catalysis - heterocycles - palladium - Heck reaction - hydrogenation
- 1 For a review, see:
Felpin F.-X.Fouquet E. ChemSusChem 2008, 1: 718 -
2a
Lipshutz BH.Nihan DM.Vinogradova E.Taft BR.Bošković V. Org. Lett. 2008, 10: 4279 -
2b
Kantam LK.Chakravarti R.Chintareddy VR.Sreedhar B.Bhargava S. Adv. Synth. Catal. 2008, 350: 2544 -
2c
Cusati G.Wedig A.Djakovitch L. Lett. Org. Chem. 2009, 6: 77 -
2d
Jansat S.Durand J.Favier I.Malbosc F.Pradel C.Teuma E.Gómez M. ChemCatChem 2009, 1: 244 -
2e
Climent MJ.Corma A.Iborra S.Mifsud M.Velty A. Green Chem. 2010, 12: 99 -
3a
Felpin F.-X.Ibarguren O.Nassar-Hardy L.Fouquet E. J. Org. Chem. 2009, 74: 1349 -
3b
Ibarguren O.Zakri C.Fouquet E.Felpin F.-X. Tetrahedron Lett. 2009, 50: 5071 - 4
Felpin F.-X.Coste J.Zakri C.Fouquet E. Chem. Eur. J. 2009, 15: 7238 - 5
Wipf P.Hopkins CR.Phillips EO.Lazo JS. Tetrahedron 2002, 58: 6367 - 6
Alaimo PJ.O’Brien R.Johnson AW.Slauson SR.O’Brien JM.Tyson EL.Marshall A.-L.Ottinger EC.Chacon JG.Wallace L.Paulino CY.Connell S. Org. Lett. 2008, 10: 5111 -
10a
Hanson P.Rowell SC.Taylor AB.Walton PH.Timms AW. J. Chem. Soc., Perkin Trans. 2 2002, 1126 -
10b
Hanson P.Jones JR.Taylor AB.Walton PH.Timms AW. J. Chem. Soc., Perkin Trans. 2 2002, 1135 - 11
Sakai H.Tsutsumi K.Morimoto T.Kakiuchi K. Adv. Synth. Catal. 2008, 350: 2498 - 12 Heck couplings of aryl diazonium
salts have been described with a Pd(II)/C catalyst, see:
Felpin F.-X.Fouquet E.Zakri C. Adv. Synth. Catal. 2008, 350: 2559 -
13a
Taylor RH.Felpin F.-X. Org. Lett. 2007, 9: 2911 -
13b
Felpin F.-X.Fouquet E.Zakri C. Adv. Synth. Catal. 2009, 351: 649 - 14
Zulauf A.Mellah M.Schulz E. Chem. Commun. 2009, 6574
References and Notes
General Procedure for the Cyanation of Iodoaryls 7a,b: To a solution of iodoaryl 7a,b (7.00 mmol, 1 equiv) in DMF (7 mL) was added CuCN (689 mg, 7.7 mmol). The resulting mixture was stirred for 4-5 h at 130 ˚C and then filtered. The solution was diluted with CH2Cl2 (21 mL) and hydrolyzed with 5% aq NH4OH solution. After being stirred for 30 min, the aqueous layer was extracted with CH2Cl2 (3 ×). The collected organic extracts were dried (MgSO4) and concentrated under reduced pressure. Purification by flash chromatography gave the expected products 8a,b.
8General Procedure for the Preparation of Acrylates 1a,b: To a solution of ester 8a,b (10 mmol, 1 equiv) in toluene (13 mL) were added HCHO (28 mmol, 2.8 equiv), Bu4NI (0.2 mmol, 0.04 equiv) and K2CO3 (30 mmol, 3 equiv) at r.t. The resulting mixture was stirred for 5 h at 50 ˚C. After cooling to r.t., H2O (10 mL) was added and the aqueous phase was extracted with toluene (2 × 20 mL). The collected organic extracts were dried (MgSO4), filtered and concentrated under reduced pressure to give the corresponding products 1a,b which were purified by flash chromatography.
9General Procedure for the Preparation of 4-Benzyl-1,2-dihydroisoquinolin-3-ones 5a-h: Acrylate 1a,b (1 mmol) and Pd(OAc)2 (5 mol%) were added to a solution of diazonium salt (1.2 mmol) in MeOH (5 mL). The reaction was stirred for 12 h at 40 ˚C, charcoal (110 mg) was added and the resulting mixture was stirred under H2 (balloon, 1 atm) for 24 h at 50 ˚C. After cooling to r.t., K2CO3 (2 mmol) was added in one portion and the heterogeneous mixture was stirred for 2 h, filtered, and purified by flash chromatography to give the corresponding 4-benzyl-1,2-dihydroisoquinolin-3-ones 5a-h.