An Improved and Easy Method for the Preparation of 2,2-Disubstituted 1-Nitroalkenes

• Published in: Journal of organic chemistry 2001-03, Vol.66 (6), p.1984-1991
• Main Authors: Lin, Wen-Wei, Jang, Yeong-Jiunn, Wang, Yeh, Liu, Ju-Tsung, Hu, Shin-Ru, Wang, Lian-Yong, Yao, Ching-Fa
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo001215u

Reactions of ketones 1, nitromethane 2, and catalytic amount of piperidine 3 in the presence of mercaptan 6 generate β-nitroalkyl sulfides 7−9. At 0 °C and by the use of dichloromethane as solvent, β-nitroalkyl sulfides 7−9 can be oxidized by m-chloroperoxybenzoic acid (m-CPBA) 10 to generate β-nitroalkyl sulfoxides 11−13 and undergo elimination in carbon tetrachloride solution to produce medium to high yield of 2,2-disubstituted 1-nitroalkenes 5. The irreversibility of the synthetic mechanism not only can overcome the reversibility of the Henry reaction in the synthesis of 2,2-disubstituted 1-nitroalkenes 5 but also can generate the major products “exo-nitro olefins” 5c−e when cyclic ketones 1c−e were used. Under similar conditions, medium to high yield of 5-substituted-2-nitromethyl-2-phenylthioadamantane 17 also can be prepared from the reaction of 5-substituted-2-adamantanones 15, nitromethane 2, piperidine 3, thiophenol 6a. The intermediate 17 can be oxidized by m-CPBA 10 in dichloromethane solution and then undergo elimination at room temperature or can be dissolved in solvent, coated on silica gel, and then heated at 90−100 °C to generate 5-substituted-2-nitromethyleneadamantane 16.