Diethyl 2- propane 3-dioate

Other 1,3-dicarbonyl compounds also exist largely in the enol form. In some examples there is an additional stabilizing factor, intramolecular hydrogen bonding. Diethyl malonate (diethyl propane-dioate) has a symmetrical enol stabilized by conjugation. The enol form is also stabilized by a very diethyl maionate favourable intramolecular hydrogen bond in a six-membered ring. 

The Knoevenagel reaction (Scheme 6.20) involves the reaction of aromatic aldehydes with a variety of molecules CH2XY. The groups X and Y may be the same or different, but are invariably electron withdrawing, so creating an activated methylene group from which the carbanion CHXY is produced. The reaction is usually carried out in pyridine solution, with piperidine as the basic catalyst. The reactions of benzaldehyde with propane-1,3-dinitrile [malononitrile, CH2(CN)2] and diethyl propane-1,3-dioate [diethyl malonate, CH.,(CO,Et)2] are illustrative. In both cases, manipulation of the CH=CX2 group in the product allows the synthesis of other compounds. 

Diethyl 2-ethyl propane-1,3-dioate EtCH(C(0)0Et)2 91.5 382.8 AOP 1996ZHA/BOR... 

Diethyl 2,2-dichloro propane-l,3-dioate Cl-CCl(C(0)0Et)2 67.3 281.6 Correlation 1995DEN... 

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