Download PDF
Synlett 2007(7): 1115-1117  
DOI: 10.1055/s-2007-973901
LETTER
© Georg Thieme Verlag Stuttgart · New York

Samarium Metal Promoted Facile C-Acetylation of Baylis-Hillman Adducts in the Presence of Iron(III) Chloride and Iodine

Shaoyu Li, Jian Li, Xueshun Jia*
Department of Chemistry, Shanghai University, Shanghai 200444, P. R. of China
Fax: +86(21)66132797; e-Mail: xsjia@mail.shu.edu.cn;
Further Information

Publication History

Received 2 January 2007
Publication Date:
13 April 2007 (online)

    Permissions and Reprints All articles of this category

Abstract

A novel and efficient strategy for the C-acetylation of Baylis-Hillman adducts has been described. Promoted by Sm(0)/Ac2O/FeCl3/I2, the present method allows for the efficient con­version of Morita-Baylis-Hillman adducts to their corresponding 2-alkylidene-4-oxoalkanoate derivatives and reduction products.

Key words

Baylis-Hillman adduct - metallic samarium - C-acetylation - stereoselective

10

All new compounds were characterized by 1H NMR, 13C NMR, IR spectroscopy, and elemental analysis.

11

The stereochemistry of product 2 was all E, as was that of product 3. [9c] The 1H NMR spectrum of 2 was in good agreement with the reported data. [5]

14

General Procedure for C-Acetylation of Baylis-Hillman Adducts
To a stirred solution of 6 mmol Sm powder (0.9 g) and
6 mmol Ac2O (0.6 g) in 15 mL THF, 5 mol% FeCl3, 4 mol% I2 and 1 mmol Baylis-Hillman adduct 1 were added. The resulting mixture was then allowed to reflux in the air. Until completion of the reaction, 3 mL HCl (1 M) was then added to quench the reaction and the mixture was successively exacted with CH2Cl2 (3 × 20 mL). The organic phase was washed with 15 mL sat. brine, dried over anhyd Na2SO4, and filtered. The solvent was removed under reduced pressure to give the crude products, which were purified by column chromatography using EtOAc and PE (1:10) as eluent. Selected spectroscopic data for compounds 2 follow.
Compound 2a (R = Ph): 1H NMR (500 MHz, CDCl3): δ = 7.93 (s, 1 H), 7.37-7.27 (m, 5 H), 3.80 (s, 3 H), 3.62 (s, 2 H), 2.25 (s, 3 H). 13C NMR (500 MHz, CDCl3): δ = 206.1, 167.8, 142.2, 135.0, 128.9, 128.7, 128.6, 126.6, 52.2, 42.5, 30.1. IR (film): 3058, 2952, 2847, 1703, 1639, 1575, 1492, 1437, 1359, 1264, 1098, 764, 700 cm-1.
Compound 2b (R = 3-MeOC6H4): 1H NMR (500 MHz, CDCl3): δ = 7.90 (s, 1 H), 7.30-6.84 (m, 4 H), 3.81 (s, 3 H), 3.80 (s, 3 H), 3.63 (s, 2 H), 2.26 (s, 3 H). 13C NMR (500 MHz, CDCl3): δ = 206.6, 168.4, 160.1, 142.8, 136.9, 130.2, 127.4, 121.6, 115.2, 114.5, 55.8, 52.8, 43.2, 30.7. IR (film): 3001, 2953, 2850, 1706, 1637, 1600, 1580, 1488, 1433, 1359, 1247, 1098, 790, 690 cm-1.