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Synlett 2002(4): 0588-0592
DOI: 10.1055/s-2002-22720
LETTER
© Georg Thieme Verlag Stuttgart · New York

Sodium Hypophosphite Decomplexation of Acetylenebiscobalthexacarbonyls to cis-Olefins

Shigeyuki Takai, Poonsakdi Ploypradith, Akinari Hamajima, Kazunobu Kira, Minoru Isobe*
Laboratory of Organic Chemistry, School of Bioagricultural Sciences, Nagoya University Chikusa, Nagoya 464-8601, Japan
Fax: +81(52)7894111; e-Mail: isobem@agr.nagoya-u.ac.jp;
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Publication History

Received 1 February 2002
Publication Date:
05 February 2007 (online)

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Abstract

Reductive decomplexation of acetylenebiscobalthexa-carbonyl is best achieved with tri-n-butyltin hydride. Instead of this toxic reagent, sodium hypophosphite monohydrate has proved to be a safe, effective, and economical reagent for such a reductive decomplexation of biscobalthexacarbonyl acetylenes into the corresponding cis-olefins.

Key words

acetylenebiscobalthexacarbonyl - sodium hypophosphite - reductive decomplexation - Nicholas reaction - ciguatoxin

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Aldrich, 500 g, $ 430 in Japan.

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WAKO, 500 g, $ 18 in Japan.

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A reductive decomplexation of 24 with n-Bu3SnH was successful to give 33, which was trans-olefin. A possible mechanism is shown below (Figure [2] ).

Figure 2

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Physical data for 29. IR (KBr): 3447, 2925, 2359, 2344, 2094, 2055, 2028, 1734, 1560, 1285, 1144 cm-1. 1H NMR (CDCl3, 400 MHz) δ 1.19 (9 H, s, -OPiv), 1.22 (9 H, s, -OPiv), 1.64 (1 H, dddd, J = 14.5, 9.0, 6.0, 5.0 Hz, H-14), 2.15 (1 H, dddd, J = 14.5, 7.5, 7.5, 2.5 Hz, H-14), 2.84 (1 H, br-s, -OH), 2.87 (1 H, dd, J = 15.5, 9.5 Hz, H-8), 2.94 (1 H, dd, J = 9.0, 9.0 Hz, H-12), 3.29 (1 H, ddd, J = 9.0, 9.0, 2.5 Hz, H-13), 3.35 (3 H, m, -OMe), 3.39 (1 H, ddd, J = 9.5, 9.0, 4.0 Hz, H-9), 3.47-3.60 (2 H, m, H-15), 3.52 (1 H, dd, J = 9.0, 9.0 Hz, H-10), 3.59 (3 H, m, -OMe), 3.59 (1 H, dd, J = 15.5, 4.0 Hz, H-8), 3.64 (1 H, dd, J = 9.0, 9.0 Hz, H-11), 4.09 (1 H, dd, J = 11.5, 7.0 Hz, H-1), 4.29 (1 H, dd, J = 11.5, 3.5 Hz, H-1), 5.06 (1 H, dd, J = 4.5, 1.5 Hz, H-5), 5.58 (1 H, ddd, J = 7.0, 6.5, 3.5 Hz, H-2), 5.86 (1 H, ddd, J = 15.5, 6.5, 1.5 Hz, H-3), 5.96 (1 H, ddd, J = 15.5, 4.5, 1.0 Hz, H-4). 13C NMR (CDCl3, 100 MHz) δ 27.09, 27.11, 29.70, 32.01, 38.67, 38.82, 38.87, 58.53, 60.45, 64.71, 68.95, 70.84, 74.95, 75.02, 77.50, 77.88, 81.10, 82.59, 87.47, 91.78, 99.87, 125.80, 131.89, 177.18, 178.07, 198.74, 199.23, 201.69. ESI Q-TOF MS calcd for C33H43Co2O15 [M + H]+ 797.127, found 797.128. [α]D 25 +170.0 (c 0.05, CHCl3).

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Physical data for 30. IR (KBr): 3448, 2962, 2925, 2360, 2344, 1734, 1718, 1282, 1144, 1108 cm-1. 1H NMR (CDCl3, 400 MHz) δ 1.18 (9 H, s, -OPiv), 1.21 (9 H, s, -OPiv), 1.64 (1 H, dddd, J = 14.0, 9.0, 5.5, 5.5 Hz, H-14), 2.12 (1 H, dddd, J = 14.0, 7.5, 7.5, 3.0 Hz, H-14), 2.32 (1 H, m, H-8), 2.58 (1 H, ddd, J = 15.5, 8.5, 3.5 Hz, H-8), 2.75 (1 H, br-s, -OH), 2.92 (1 H, dd, J = 9.0, 9.0 Hz, H-12), 3.12 (1 H, ddd, J = 10.5, 9.0, 3.5 Hz, H-9), 3.29 (1 H, m, H-13), 3.29 (1 H, dd, J = 9.0, 9.0 Hz, H-10), 3.33 (3 H, s, -OMe), 3.50 (1 H, dd, J = 7.5, 5.5 Hz, H-15), 3.52 (1 H, dd, J = 9.0, 7.5 Hz, H-15), 3.59 (3 H, s, -OMe), 3.64 (1 H, dd, J = 9.0, 9.0 Hz, H-11), 4.09 (1 H, dd, J = 11.5, 7.0 Hz, H-1), 4.27 (1 H, dd, J = 11.5, 3.5 Hz, H-1), 4.50-4.54 (1 H, m, H-5), 5.51 (1 H, ddd, J = 6.5, 6.0, 3.5 Hz, H-2), 5.72 (1 H, ddd, J = 15.5, 6.0, 1.5 Hz, H-3), 5.77 (1 H, ddd, J = 11.0, 4.5, 4.0 Hz, H-6), 5.85 (1 H, dddd, J = 11.0, 8.5, 3.5, 2.5 Hz, H-7), 5.88 (1 H, ddd, J = 15.5, 5.5, 1.5 Hz, H-4). 13C NMR (CDCl3, 100 MHz) δ 27.14, 29.69, 32.08, 33.78, 38.81, 58.52, 60.41, 64.61, 69.09, 70.92, 73.99, 75.39, 77.15, 83.36, 87.47, 125.69, 128.55, 133.76, 135.17, 177.28, 178.04. ESI Q-TOF MS calcd for C27H44NaO9 [M + Na]+ 535.288, found 535.289. [α]D 27 +60.7 (c 0.11, CHCl3).