21.9Alkylation of ethyl acetoacetate with 1,4-dibromobutane gives a product that can cyclize to a fve-membered ring.Saponifcation followed by decarboxylation gives cyclopentyl methyl ketone.21.10The last step in the synthesis of pentobarbital is the reaction of the appropriately substituted deriva-tive of diethyl malonate with urea.The dialkyl derivative of diethyl malonate is made in the usual way. It does not matter whether theethyl group or the 1-methylbutyl group is introduced frst.CH2(COOCH2CH3)2Diethyl malonateCH3CH2CH2CHCH3CH3CH2C(COOCH2CH3)2Diethyl 2-ethyl-2-(1-methylbutyl)malonate2. NaOCH2CH3, CH3CH2Br1. NaOCH2CH3, CH3CH2CH2CHCH3Br1COCH2CH3COCH2CH3
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