Synlett 2010(10): 1539-1543  
DOI: 10.1055/s-0029-1219926
© Georg Thieme Verlag Stuttgart ˙ New York

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

Julia Laudiena, Eric Fouqueta, Cécile Zakrib, François-Xavier Felpin*a
a Université de Bordeaux, UMR CNRS 5255, Institut des Sciences Moléculaires, 351 Cours de la Libération, Talence 33405, France
Fax: +33(5)40006286; e-Mail:;
b Université de Bordeaux, CNRS, Centre de Recherche Paul Pascal, Avenue Schweitzer, 33600 Pessac, France
Further Information

Publication History

Received 16 March 2010
Publication Date:
10 May 2010 (online)


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.

    References and Notes

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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.


General 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.


General 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.