Table 1. Pairwise r.m.s. differences between starting and final structures of 1 and 2^a.

	A-formb	B-formc	1d
B-formc	5.1 Å
1d	3.1 Å	2.7 Å
2e	3.7 Å	2.4 Å	1.3 Å

^aPairwise r.m.s. difference values were calculated between all heavy atom coordinates.

^bEnergy minimized A-form starting structure for 1 or 2.

^cEnergy minimized B-form starting structure for 1 or 2.

^dFinal structure of 1. See text for details.

^eFinal structure of 2.