ISSN:
1573-8353
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract By optimization of the geometry of 2, 5-dioxabicyclo[2. 2.1]heptane-3.6-dione (1) with an ab initio (RHF/6-31 G') calculation, we have found that a single synchro(+, +)-twist form (A) corresponds to the (1 R,4R)-enantiomer (the dihedral angles of the lactone bridges areϕ 0 = 2.6°). According to MM2(91) and MM3(92) calculations, (1R,4R)-1 exists as the s-ynchro(+, +)-A-twist (ϕ 0 = 3.9°) and the synchro(-, -)-B-twist (ϕ = -3.8°) forms, respectively. Investigating the torsional energy surface of the dilactone 1 (MM2(91)), we found only the (1R,4R,P)-diastereomeric form (A), which is stabilized compared with the (1R,4P,M) form (B) (probably as a result of the more preferred dipole-dipole interaction of the carbonyl groups). According to the calculated puckering coordinates, the five-membered and six-membered moieties of the bicycle 1 are flattened compared with norbornane.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01168620
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