2 ISOMERIC [2.1]CRYPTAHEMISPHERAND DIAMIDES

The geometrical isomers of 35-trimethoxy-5,10,15-trimethyl-22,25,30-tr ioxa-1, 7(33),8,10,12(34),13,15,17(35)-nonaene-2,18-dione, C36H44N2O8, are intermediates in the synthesis of reduced cryptahemispherands. Th eir amide groups are characteristically coplanar with their attached a toms. Consequently, the N atoms in these structures are neither exo no r endo, unlike the N atoms in most other cryptands and cryptahemispher ands. In the isomer formed in smaller amount, (II), the N atoms are ab out 1 Angstrom closer to each other than in the other structure, (I), because the five-atom bridge between these N atoms is so constrained a s to draw them together. Structure (I) is more dense than structure (I I) by about 9%.