X-ray crystal structure determination of the more laevorotatory diastereoisomer of 2′-O-tetrahydropyranyladenosine. Correlation of physical properties of tetrahydropyranyl ethers with absolute configuration

Abstract

The structure of the more laevorotatory diastereoisomer of 2′-O-tetrahydropyranyladenosine has been determined by X-ray diffraction using direct methods. The final R factor is 3·9% for 1810 observed reflexions. Estimated standard deviations were 0·003–0·006 Å in bond-lengths not involving hydrogen atoms. The adenosine dimensions and conformation are compared with other X-ray structure determinations. The absolute configuration of the acetal carbon centre [C(2″)] is deduced to be S, which agrees with indications from optical rotation measurements. The compound crystallises in space group P2₁2₁2₁ with Z= 4 in a unit cell of dimensions: a= 10·942 ± 0·003, b= 28·235 ± 0·005, 5·292 ± 0·001 Å.