Synthesis 2009(14): 2324-2328  
DOI: 10.1055/s-0029-1216856
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

A Safe, Convenient and Efficient One-Pot Synthesis of α-Chloroketone Acetals Directly from Ketones Using Iodobenzene Dichloride

Jun Yu, Chi Zhang*
The State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. of China
Fax: +86(22)23499247; e-Mail: zhangchi@nankai.edu.cn;
Further Information

Publication History

Received 22 January 2009
Publication Date:
29 May 2009 (online)

Abstract

Various ketones, including aliphatic and aromatic ketones, can be directly converted into their corresponding α-chloroketone acetals in high to excellent yields using iodobenzene dichloride in ethylene glycol in the presence of 4 Å molecular sieves at room temperature.

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One referee surmised that molecular chlorine might be the active species in our system and advised us to check this possibility by carrying out the reaction showed in Scheme  [³] in the presence of 4 Å MS. Accordingly, 4′-methylaceto­-phenone was treated with 1.1 equivalents of molecular chlorine in ethylene glycol in the presence of 4 Å MS at room temperature. After 20 hours, 48% of starting material was recovered and only 7% of the desired cyclic ketal of
α-chloroketone was obtained, together with 2-methyl-2-p-tolyl-1,3-dioxolane, which formed as the major product (40%). Apparently, this result is distinct from that observed with our PhICl2/ethylene glycol/4 Å MS system under which the same cyclic ketal of α-chloroketone was obtained in 95% yield within only 30 minutes (Table  [¹] , entry 5). Therefore, we believe that the mechanism shown in Scheme  [¹] is still preferable.