Diethyl benzylidenemalonate

Although the Michael addition of metal ynolates to a,/ -unsaturated carbonyl compounds is expected to give six-membered cycloadducts, 1,2-addition to carbonyl groups usually precedes 1,4-addition. The cycloaddition of the lithium-aluminum ate complex of silyl-substimted ynolate 112 with ethyl benzylideneacetoacetate (113), which is doubly activated by the ester and keto functions, gives the y-lactone 114 via a [4 4- 2] type cycloaddition (equation 46). Diethyl benzylidenemalonate (115) affords the uncyclized ketene 116 by reaction with 112 (equation 47). This could be taken as evidence for a stepwise mechanism for equation 46. ... 

Diethyl (a-cyanobenzyl)malonate 118 Diethyl benzylidenemalonate (24.5 g) is dissolved in ethanol (250 ml), and a solution of potassium cyanide (6.5 g) in water (100 ml) is added. To the resulting clear liquid, 30% hydrochloric acid (11 g), diluted with water (50 ml), is added gradually and with cooling. The mixture is set aside for some days. Then the weakly acidic liquid, which barely smells of hydrogen cyanide, is treated with sufficient water to cause incipient turbidity. After 24 h a considerable yield of condensation product has separated as needles, which, when collected and washed with ethanol, melt at 48.5°. 

Ethyl ethoxymethylenemalonale (EMME) allowed to react at -60 to -50 in ether with phenylmagnesium bromide prepared from bromobenzene and Mg diethyl benzylidenemalonate. Y 50.5%. - Whether simple or double conjugate addition (to a satd. product) occurs appears to depend on the structures of both the organometallic compd. as well as the conjugated enolether. F. e., also addition of 2 molecules, s. D. P. Nabar and S. V. Sunthankar, Bull. Chem. Soc. Japan 42, 2991 (1969). 

The kinetics of reactions of substituted ethyl arylacetates with quinone methides and structurally related diethyl benzylidenemalonates and of reactions of pyridinium, iso-quinolinium, and quinolinium ylides with diarylcarbenium ions, quinone methides, and arylidene malonates have been studied using solvent DMSO. Pyridinium substitution is found to have a similar effect on the reactivity of carbanionic reaction centres as alkoxycarbonyl substitution. The structures and ambident reactivities of azolium eno-lates have been investigated. ... 

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