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Synlett 2002(10): 1694-1696
DOI: 10.1055/s-2002-34239
LETTER
© Georg Thieme Verlag Stuttgart · New York

Highly Efficient Allylation of Aldehydes and Three-Component Synthesis of Homoallylamines Using Bismuth Triflate Catalyst

Boyapati M. Choudary*, Sridhar Chidara, Ch. V. Raja Sekhar
Indian Institute of Chemical Technology, Hyderabad - 500 007, India
Fax: +91(40)7160921; e-Mail: choudary@iict.ap.nic.in;
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Publication History

Received 1 August 2002
Publication Date:
23 September 2002 (online)

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Abstract

Bismuth triflate catalyzed allylation of a variety of aldehydes and aldimines using allyltributylstannane has been presented. The reaction proceeds rapidly and yields corresponding homoallylic alcohols and homoallylic amines in good yields. The bismuth triflate displays manifold activity over the La, Yb, and Sc triflates. The catalyst is reused for allylation of aldehydes and aldimines without significant loss of catalytic activity for four cycles.

Key words

allylation - aldehydes and aldimines - bismuth triflate - Bronsted acids - turnover frequency

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Typical Experimental Procedure for the Allylation of Aldehydes: To a stirred solution of p-chlorobenzaldehyde (1 mmol), benzoic acid (1 mmol) and allyltributylstannane (1.2 mmol) in acetonitrile (5 mL) at r.t. was added bismuth triflate (2 mol%). The mixture was stirred at r.t. until reaction was completed as indicated by TLC. The catalyst, which was precipitated at the end of the reaction, was filtered off. The filtrate was concentrated under vacuum to obtain a crude product and was purified by column chromatography (10% ethyl acetate-hexane) (164 mg, 90%). 1H NMR (200 MHz, CDCl3) δ 2.01(d, 1 H, OH), 2.52 (m, 2 H, CH2), 4.75 (t, 1 H,CH), 5.14-5.20 (m, 2 H, 2 vinyls), 5.82 (m, 1 H, vinyl), 7.20-7.30 (m, 4 H, aromatic) [Lit [10a] ].

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Typical Experimental Procedure for the One-Pot Allylation of Aldimines: To a stirred solution of p-chlorobenzaldehyde (1 mmol), benzoic acid (1 mmol), allyltributylstannane (1.2 mmol) and o-chloroaniline (1 mmol) in acetonitrile (5 mL) at r.t. was added bismuth triflate (2 mol%). The mixture was stirred at r.t. until reaction was completed as indicated by TLC. The catalyst, which was precipitated at the end of the reaction, was filtered off. The filtrate was concentrated under vacuum to obtain a crude product and was purified by column chromatography (10% ethyl acetate-hexane) (189 mg, 65%). 1H NMR (200 MHz, CDCl3) δ 2.52 (m, 2 H, CH2), 4.40 (t, 1 H, CH), 5.14-5.20 (m, 2 H, 2 vinyls), 5.80 (m, 1 H, vinyl), 6.20 (d, 1 H, aromatic), 6.6 (m, 2 H, aromatic), 6.80-7.00 (m, 1 H, aromatic), 7.20-7.30 (m, 4 H, aromatic) [Lit [16] ].