Synlett 2011(7): 943-946  
DOI: 10.1055/s-0030-1259716
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Chiral P-Containing Palladacycle-Catalyzed Asymmetric Ring-Opening Reactions of Oxabicyclic Alkenes with Alkenyl Boronic Acids

Xiao-Jun Huang, Dong-Liang Mo, Chang-Hua Ding, Xue-Long Hou*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. of China
Fax: +86(21)54925100; e-Mail: xlhou@sioc.ac.cn;
Further Information

Publication History

Received 9 December 2010
Publication Date:
10 March 2011 (online)

Abstract

An efficient palladacycle-catalyzed asymmetric ring-opening reaction of oxabicyclic alkenes with alkenyl boronic acids was developed to afford the corresponding products in good to excellent yields and enantioselectivity.

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P-containing palladacycle 5 was provided by Professor Christopher J. Richards.

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A Representative Procedure for Palladacycle 4 Catalyzed Asymmetric Ring-Opening Reactions of Oxabicyclic Alkenes with Alkenyl Boronic Acids (Table 2, Entry 3) To a mixture of 7-oxabicycle alkene 1a (28.8 mg, 0.2 mmol), (E)-hex-1-enylboronic acid (2c, 38.4 mg, 0.3 mmol), and palladacycle 4 (6.0 mg, 5 mol%) in CH2Cl2 (3 mL) was added a solution of CsF in H2O (5 M, 0.1 mmol, 20 µL) at 0 ˚C with stirring. The reaction was monitored by TLC until completion. The solvent was removed under reduced pressure. The residue was purified by column chromatog-raphy (PE-CH2Cl2 = 2:1, v/v) to afford 42 mg of oil product 3c, 92% yield, ee: 75%. [α]D ²5 -193 (c 1.06, CHCl3). HPLC: Chiralcel OD (250 mm × 4.6 mm), n-hexane-i-PrOH = 98:2, 1.0 mL/min, 254 nm, t R = 8.7 min, 10.6 min. ¹H NMR (400 MHz, CDCl3): δ = 0.87 (t, J = 6.8 Hz, 3 H), 1.26-1.37 (m, 4 H), 1.85 (d, J = 8.0 Hz, 1 H), 2.02 (dd, J = 6.8, 14.0 Hz, 2 H), 3.08-3.13 (m, 1 H), 4.79 (t, J = 6.8 Hz, 1 H), 5.33 (dd, J = 8.8, 15.2 Hz, 1 H), 5.69-5.76 (m, 1 H), 5.93 (dd, J = 4.8, 9.6 Hz, 1 H), 6.48 (d, J = 9.6 Hz, 1 H), 7.06 (t, J = 3.6 Hz, 1 H), 7.22-7.25 (m, 2 H), 7.43 (t, J = 4.0 Hz, 1 H). MS (EI): m/z (rel.) = 228 (45) [M+], 167 (67), 165 (30), 146 (100), 131 (53), 128 (42), 118 (69), 115 (46).