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20.2.12.1.1.1.2 Variation 2: Use of Triethylamine and Metal Salts

DOI: 10.1055/sos-SD-020-00556

Beignet, J.Science of Synthesis, (200720570.

The use of a combination of triethylamine and magnesium chloride or lithium bromide is sufficient to deprotonate the methylene group of bis(trimethylsilyl) malonate (1) (Scheme 2).[‌21‌] By analogy with the previous method (see Section 20.2.12.1.1.1.1), acylation of the resulting complex with an acid chloride is then possible and occurs smoothly at 0°C. Final acidic workup furnishes the product in moderate to good yields. The use of less reactive acylating agents, such as carbonates and 1-acetyl-1H-imidazoles, is less efficient. The preparation of acyl carbonates may be carried out in situ. This route offers another advantage over the classical route employing butyllithium as a base (see Section 20.2.12.1.1.1.1). Namely that the acidic nature of the product can be accommodated by the use of 2 equivalents of triethylamine, thus avoiding the necessity of the twofold excess of the malonate.

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