Conformational behavior of saturated

The conformational behavior of saturated heterocycles resembles that of saturated carbocycles in many but not all aspects. Indeed, the heteroatom(s) influence(s) the relative energy of the various conformers (low-energy forms as well as transition states), and may contribute specific interactions with the substituent(s). 

Ab initio, semi-empirical, and molecular mechanics calculations have been used extensively in the study of nine-membered heterocycles. Theoretical studies of heteronines have centered on the question of their aromaticity, which was surveyed as a part of general heterocycles aromaticity study <2004CRV2777>. Another important aspect is the conformation of the nonconjugated compounds (see Section 14.10.4.3). Computational aspects of conformational behavior of saturated nine-membered rings and nine-membered rings containing one torsional constraint were the part of the review <1999MI(5)89>. 

Rules to predict the conformational behavior of saturated seven-membered heterocycles 05ARK(6)88. 

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