4,8-Dioxo-6,6-dimethyl-1-benzyl-5,7-dioxa-spiro<2,5>octan;Isopropylidenacylal der 2-Benzyl-cyclopropan-dicarbonsaeure-(1,1);2-benzyl-6,6-dimethyl-5,7-dioxaspiro[2.5]octane-4,8-dione
The reaction of 5-arylidene(alkylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones (1) (Meldrum's acid derivatives) with dimethylsulfoxonium methylide gave 1- aryl(alkyl) - 6,6 - dimethyl - 4,8 - dioxo - 5,7 -dioxaspiro [2.5] octanes (2) which, on treatment with sodium methoxide or ammonium hydroxide, gave exclusively E-1-methoxy-carboyl-2-aryl-cyclopropanecarboxylic acids (4) or Z-1-carbamoyl-2-aryl(alk