Diethyl carbonate alkoxycarbonylation

Ester condensation with diethyl carbonate introduces an alkoxycarbonyl group.760 Diethyl carbonate and 2-octanone in the presence of sodamide give ethyl 3-oxononanoate in 52% yield 761 and in a similar reaction nitriles afford cyano esters in yields up to 87%,762 e.g. ... 

Deprotonation of methylene groups containing two electron-withdrawing alkoxycarbonyl groups with an appropriate base easily converts them into their corresponding enolate anions. These enolate anions are able to attack carbon electrophiles to form new C —C bonds. One of the important applications of this reaction is to construct small carbocyclic rings, in particular cyclobutanes. For example, intermolecular condensation of l,3-dibromo-2,2-dimethylpropane (1) and the dipotassium salt of diethyl malonate (2) gives diethyl 3,3-dimethylcyclobutane-l,l-dicarboxylate (3).18... 

Dialkyl l-(hydroxycarbonyl)methylphosphonates have been the subject of numerous investigations, with the efforts largely confined to diethyl l-(hydroxycarbonyl)methylphosphonate, whose reactivity parallels that of a-substituted derivatives. Several procedures for the synthesis of diethyl 1-(hydroxycarbonyl)methylphosphonate have been developed. They include the hydrogenolysis of the benzyloxycarbonyl ester (EtOH, Pd/C, H2), the alkaline hydolysis of alkoxycarbonyl ester (KOH or NaOH, EtOH, room temperature), and the addition of carbon dioxide to... 

Unquestionably, one of the most attractive synthetic methods for the preparation of dialkyl 2-(alkoxycarbonyl)ethylphosphonates involves the conjugate addition of a dialkyl phosphite to the carbon-carbon double bond of a,p-unsaturated carboxylates (Pudovik reaction, Scheme 8.44). In the presence of EtONa, diethyl phosphite reacts vigorously with acrylate in EtOH to give the Michael addition product in 84% yield. The reaction is applied with success to the synthesis of dialkyl 2-(alkoxycarbonyl)ethylphosphonates bearing a large variety of acyclic (symmetric - or disymmetric 30 or cyclic (symmetric or disynunetric ) substituents at phosphorus. 

Intramolecular acylation. When a carbonate ester containing an alkyne or allene unit" at the proper length is submitted to i-PrMgBr/( -PrO)4Ti, the multiple bond is metallated and becomes nucleophilic such that internal attack on the carbonyl group results in O —> C transfer of the alkoxycarbonyl group. Diethyl alkynyhnalonates also undergo a similar reaction. ... 

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