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Synlett 2008(9): 1407-1411  
DOI: 10.1055/s-2008-1072753
LETTER
© Georg Thieme Verlag Stuttgart · New York

Regiocontrolled Addition of Carbonyl Compounds with Allylic Indium Generated by Hydroindation of 1,3-Dienes

Naoki Hayashia, Hiroyuki Hondaa, Ikuya Shibata*b, Makoto Yasudaa, Akio Baba*a
a Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
b Research Center for Environmental Preservation, Osaka University, 2-4 Yamadaoka, Suita, Osaka 565-0871, Japan
Fax: +81(6)68798978; e-Mail: shibata@epc.osaka-u.ac.jp;
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Publication History

Received 30 January 2008
Publication Date:
07 May 2008 (online)

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Abstract

Allylic indiums, generated by a conjugate hydroindation of 1,3-dienes by HInCl2, reacted with carbonyl compounds in a one-pot treatment. Both γ- and α-adducts can be obtained depending upon the conditions used.

Key words

allylation - hydrides - indium - ketones - regioselectivity

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Typical Procedure A 10 mL round-bottom flask charged with InCl3 (2.0 mmol) was dried by heating to 110 °C under reduced pressure (1 mmHg) for 1 h. After the nitrogen was filled, THF (2 mL) was added to dissolve InCl3. To the mixture was added Bu3SnH (2.0 mmol) at -78 °C. The mixture was then stirred for 10 min to prepare dichloroindium hydride (HInCl2). After the solution was warmed up to r.t., 2,3-dimethyl-1,3-butadiene (1a, 4.0 mmol) was added and the resulting mixture was stirred for 5 h. Then benzil (2b, 1.0 mmol) was added and stirred for 14 h. The resulting mixture was quenched by aq 1 N HCl (5 mL) and extracted with Et2O
(3 × 10 mL). The combined organic layer was treated with aq NH4F and then the precipitate was filtered to remove the tin compound. The filtrate was extracted with Et2O and dried over MgSO4. Concentration followed by silica gel column chromatography eluting with hexane-EtOAc (90:10) afforded 4ab as a solid.

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Analytical and Spectroscopic Data of Selected Compounds Compound 3ab: mp 65-66 °C. IR (KBr): 3494 (OH), 1685 (C=O) cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.67-7.59 (m, 4 H), 7.37-7.23 (m, 6 H), 5.12 (s, 1 H), 5.02 (s, 1 H), 3.52 (s, 1 H), 1.56 (s, 3 H), 1.46 (s, 3 H), 1.23 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 203.43, 151.81, 138.62, 138.42, 131.38, 129.46, 127.79, 127.62, 127.56, 127.15, 115.61, 83.54, 49.37, 24.49, 24.15, 22.85. MS (CI): m/z = 295 (70) [M+ + 1], 278 (22), 277 (100), 212 (20), 211 (86), 105(34). HRMS (CI, +0.9 mmu): m/z calcd for C20H23O2: 295.1698; found: 295.1707 [M+ + 1].
Compound 4ab: mp 88-89 °C. IR (KBr): 3498 (OH), 1670 (C=O) cm-1; 1H NMR (400 MHz, CDCl3): δ = 7.89-7.79 (m, 2 H), 7.63-7.53 (m, 2 H), 7.43-7.25 (m, 6 H), 3.63 (s, 1 H), 3.40 (d, J = 13.8 Hz, 1 H), 2.96 (d, J = 13.8 Hz, 1 H), 1.66 (s, 3 H), 1.61 (s, 3 H), 1.39 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 201.39, 143.14, 135.29, 132.61, 132.35, 130.32, 128.69, 127.89, 127.54, 125.11, 122.84, 81.80, 44.66, 21.22, 21.02, 19.74. MS (CI): m/z = 295 (67) [M+ + 1], 278 (22), 277 (100). HRMS (CI, +0.5 mmu): m/z calcd for C20H23O2: 295.1698; found: 295.1703 [M+ + 1].
Compound 4ac: IR (neat): 3514 (OH), 1732 (C=O) cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.65 (d, J = 8.0 Hz, 2 H), 7.35 (dd, J = 8.0, 7.5 Hz, 2 H), 7.29 (d, J = 7.5 Hz, 1 H), 3.74 (s, 3 H), 3.50 (s, 1 H), 3.10 (d, J = 13.8 Hz, 1 H), 2.87 (d, J = 13.8 Hz, 1 H), 1.68 (s, 6 H), 1.60 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 175.59, 142.20, 131.19, 128.08, 127.58, 125.64, 122.15, 78.00, 52.91, 44.71, 21.11, 21.00, 19.48. MS (EI, 70 eV): m/z = 248 (1) [M+], 105 (100), 84 (39), 77 (23). HRMS (EI, +0.2 mmu): m/z calcd for C15H20O3: 248.1412; found: 248.1414 [M+].
Compound 4ad: IR (neat): 3564 (OH) cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.44 (d, J = 8.0 Hz, 2 H), 7.31 (dd, J = 8.0, 7.2 Hz, 2 H), 7.23 (t, J = 7.2 Hz, 1 H), 3.67 (d, J = 9.3 Hz, 1 H), 3.57 (d, J = 9.3 Hz, 1 H), 3.37 (s, 3 H), 2.78 (s, 1 H), 2.75 (d, J = 13.8 Hz, 1 H), 2.47 (d, J = 13.8 Hz, 1 H), 1.61 (s, 3 H), 1.53 (s, 3 H), 1.41 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 145.12, 129.66, 127.85, 126.61, 125.33, 123.35, 79.10, 76.51, 59.35, 44.15, 20.92, 20.78, 20.41. MS (CI): m/z = 235 (1) [M+ + 1], 217 (100), 151 (32). HRMS (CI, -0.2 mmu): m/z calcd for C15H23O2: 235.1698; found: 235.1696 [M+ + 1].

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Although we tried the reaction of simple acetophenone (2e) with diene 1a in the presence of equimolar amount of Lewis basic additives such as Ph3P and HMPA, only a small amount of α-adduct 4ae was obtained at r.t. So we think that intramolecular coordination is more important than intermolecular coordination by ligand.