Cross-pinacol-type coupling reactions between α,β-unsaturated ketones and aldehydes with low-valent metals

✍ Scribed by Kazuhiko Takai; Ryotaro Morita; Hiroshi Matsushita; Chika Toratsu

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 120 KB
• Volume: 15
• Category: Article
• ISSN: 0899-0042
• DOI: 10.1002/chir.10148

✦ Synopsis

Treatment of an alpha,beta-unsaturated ketone and an aldehyde with chromium(II) chloride and R(3)SiCl in DMF gives cross-pinacol-type coupling products, 1,2-diols selectively. The anti/syn ratios of the produced 1,2-diols are shown to depend on the reaction temperature: at lower temperatures, the anti adduct is produced selectively, but at higher temperatures, the anti/syn ratios gradually decrease. When a combination of manganese and a catalytic amount of lead are used instead of chromium(II), 1,6-diketone, a dimer of the alpha,beta-unsaturated ketone, is produced selectively.