Crystal structure of 2,2-dimethyl-5-(3,4,5-trimethoxybenzylidene)-1,3- dioxane-4,6-dione, C16H18O7

Abstract

C16H18O7 ,t riclinic, P1 (no. 2), a =5 .334(2) A, b =1 1.674(3) A, c=1 2.510(5) A, 5 =9 6.41(3)°, 4 =9 4.93(5)°, 3 =9 2.60(2)°, V =7 70.1 A 3 , Z =2 , Rgt(F) =0 .0537, wRref(F 2 ) =0 .2641, T =2 93 K. Source of material Am ixture of malonic acid (3.08 g, 0.02 mol) and acetic acid anhydride (3 ml) in strong sulfuric acid (0.25 ml) was stirred with water at 303K. After dissolving, propan-2-one (1.16 g, 0.02 mol) was added dropwise into solution for 1h .T he reaction was allowed to proceed for 2.5 h. Th em ixture was cooled and filtered, and then an ethanol solution of 3,4,5-trimethoxybenzaldehyde (6.36g,0.02 mol) was added. The solution was then filtered and concentrated. Single crystals were obtained by evaporation of an petroleu me ther-acetone (1:1 v/v )s olutio no f( I) at room temperature over ap eriod of several days. Discussion Meldrum's acid and its derivatives have widely used in organic synthesis owing to their interesting conformational features [1,2]. In the title compound, bond lengths and angles are in agreement with those of the similar structures [3].The dioxane ring is in a distorted envelope conformation with the C14 atom bonded to the two methyl groups forming the flap. In the crystal structure it confirms that the title compound is linked by the 1,3-dioxane ring via aC 10=C12 double bond [1.362(3)A] and the phenyl ring via a C8–C10 single bond [1.458(3)A], forming the C12–C10–C8 bond angle of 136.7(2)°. The crystal structure is stabilized by weak intermolecular C–H∏∏∏ Oh ydrogen bonds.