E. Maverick, C. Knobler, K. Trueblood
Dec 15, 1997
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Abstract
The geometrical isomers of 33,34,35-trimethoxy-5,10,15-trimethyl-22,25,30-trioxa-1,19-diazapentacyclo[17.8.51 3,7 .1 8,12 .1 13,17 ]pentatriaconta-3,5,7(33),8,10,12(34),13,15,17(35)-nonaene-2,2,18-dione, C 36 H 44 N 2 O 8 , are intermediates in the synthesis of reduced crypta-hemispherands. Their amide groups are characteristically coplanar with their attached atoms. Consequently, the N atoms in these structures are neither exo nor endo, unlike the N atoms in most other cryptands and crypta-hemispherands. In the isomer formed in smaller amount, (II), the N atoms are about 1 A closer to each other than in the other structure, (I), because the five-atom bridge between these N atoms is so constrained as to draw them together. Structure (I) is more dense than structure (II) by about 9%.