2- Alkyl -substituted malononitriles, reaction

Apart from the addition reaction to electrophilic olefins, the / -carbon atom of 1,1-enediamines can also substitute a,/ -unsaturated compounds carrying a leaving group. Schafer and Gewald129 have shown that 141 and 142 react with 143 to give product 144 in moderate to good yields (equation 54). Ketene dithioacetals derived from an alkyl cyanoacetate and malononitrile behave similarly to 143130. When imine 145 is employed, the reaction results in the formation of 146 (equation 55)129. Apparently displacement of ethoxy group and cyclocondensation by attack on the nitrile moiety are the key steps in the reaction. 

Ethoxy-5,6-dihydro-4//-l,3-oxazines (111) react with enolates and related compounds at C-2 ethanol is lost and the corresponding 2-substituted dihydro-1,3-oxazine is formed. Depending upon the nature of the substituent endo-exo double bond, tautomerism can be observed. Thus, a reaction with the anion of malononitrile yields the 2-alkylidene-3,4,5,6-tetrahydro-l,3-oxazine (112) rather than the 2-alkyl-5,6-dihydro-1,3-oxazine (113) (Scheme 27) <86JHC701>. 

Isothiazolo[3,4-d]thiazolidines. - N-substituted thiocarbaraoyliso-thiazolinothiones (72 R=aryl, alkyl) are produced by reaction of the appropriate isothiocyanate, sulphur, malononitrile, and NEtg in DMF at or below 50°C. Cyclisation with gives the... 

Oxo- and amino-substituted [2,3-b]-TTs (202 and 204) result from the reaction of 3-keto esters, malononitrile, ethyl cyanoacetate, or 3-ketonitriles, with alkylating agents such as ethyl bromoacetate and bromoacetonitrile, as exemplified in Scheme 49 [75],... 

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