Tributylstibine-mediated olefination of carbonyl compounds with bromomalonic ester and with dibromomalonic ester—A possible pathway through a stibonium ylide via halophilic initiation by tertiary stibines
✍ Scribed by Chen Chen; Yao-Zeng Huang; Yanchang Shen; Yi Liao
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 511 KB
- Volume
- 1
- Category
- Article
- ISSN
- 1042-7163
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✦ Synopsis
Tributylstibine can mediate the olefination of car-bony1 compounds with bromomalonic ester and with dibromomalonic ester. An initial halophilic attack of tributylstibine on the bromine of bromomalonic or dibromomalonic ester forming an ion pair of bromotributvlstibonium cation and malonic ( A ) or bromomalonic ester carbanion (B), respectively, is proposed. These ion pairs react with carbonyl compounds to achieve subsequent olefination. Alternatively, 2 eyuii, of A collapse, with elimination of malonic ester, to form stiborane D, and the ion pair B reacts with another equivalent of tributylstibine to form stiboraiie D. This last undergoes a Wittig-type reaction with carbonyl compound to achieve olefination.
In our previous communications, we reported the tributylstibine-mediated olefination reactions of carbonyl compounds with bromoacetates [ 13, bromoacetamide [2], chloroacetonitrile [3], and abromoketones [4]; the reactions of aldehydes with 3-bromobutanone to form P-hydroxyketones [ 5 ] and with trichloroacetonitrile to form a.a-dicht This paper is the 70th report on the studies of the application of elementoorganic compounds of the 15th and 16th groups in organic synthesis. * To whom correspondence should be addressed. * The reaction was carried out with 2 mmol of carbonyl compound, 2.1 mmol of dialkyl * Isolated yields by chromatography.
dibromomalonate, and 4.2 mmol of tributylstibine at ambient temperature for 0.5 h.