3-diazo-2,2,4,4-tetramethylthietane 1,1-dioxide

ethyl α-diazoiso-propylacetate

1-(1-ethoxycarbonyl-2-methylpropylidene)-2,2,3,3-tetramethyl-cyclopropane

3,5-dihydro-3,3,5,5-tetramethyl-4-(1-ethoxycarbonyl-2-methylpropylidene)pyrazole

3'-ethoxycarbonyl-3'-isopropyl-3,3,5,5-tetramethyl-3,5-dihydropyrazole-4-spiro-2'-thi-irane