Lactones, reaction with ethoxycarbonyl

Ketones.-A convenient procedure for the synthesis of 1-formylcyclo-hexenes by one-carbon homologation of the appropriate a-phenylthioketone, e.g. (53), by phosphorus-based olefination and hydrolysis has been reported (Scheme 5).31 Further investigations of the reaction of ethoxycarbonyl-methylenetriphenylphosphorane with <>-quinones have been reported.3 2 Reactions in the presence of triphenylphosphine or alcohols or acetic anhydride led to different products including lactone ylides (54) and furan derivatives (55). 

The alcoholysis of 2-phenyloxazolin-5-one has been recently reported as an interesting enzymatic reaction for opening of lactones (Scheme 19). This compound, by reaction with iV-ethoxycarbonyl 2-amino-l-butanol in the presence of a lipase in organic solvent, yields an optically active product with moderate enantioselectivity [119]. 

Aldol-type reaction of zinc esters. This titanium reagent promotes condensation of (ethoxycarbonylalkyl)iodozinc compounds (13, 220) with aldehydes or ketones to provide hydroxy esters and/or lactones. The active reagent may be (ethoxycarbonyl)alkyltriisopropoxytitanium. 

Morgan and Wolfrom isolated an a-pyrone, probably 4-acetoxy-6-(ethoxycarbonyl)-2//-2-pyrone (89), from the reaction of monoethyl DL-galactarate or its monolactone with acetic anhydride and sodium acetate at 100 °C the authors postulated the intermediate formation of an enolic lactone in this transformation.261... 

Triethyl phosphite attacks P-propiolactones at the P-carbon at 160°C to give predominantly diethyl 2-(ethoxycarbonyl)ethylphosphonate resulting from a C-0 bond cleavage of the lactone ring. - Bases such as tertiairy amines and sodium alkoxides catalyze the reaction of lactones with phosphites. ... 

The minor product formed in the reaction of NeuNAc with AcaO-pyridine has been shown to be the peracet dated 1.7-lactone.35 Benzoylation of Neu IAc can give 1,7- or 1,4-lactones depending on the conditions, and such bicyclic lactones are also formed during pivaloylation and ethoxycarbonylation. 

O-Ethylation occurs when the sodium enolates of a-formyl -y-and 8-lactones are refluxed in THF with ethyl chloroformate. iV-Ethoxycarbonylation forms the basis of a variety of reactions of nitrogenous compounds. Aziridines form N-ethoxycarbonylaziridines which are converted, on heating, to al-lylic amines (eq 13). ... 

---