𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Conformational Flexibility of the Acetoxyphenyl Group Studied by Statistical Analysis of Crystal Structure Data

✍ Scribed by Wolfgang Hummel; Aleksander Roszak; Hans-Beat Bürgi

Publisher
John Wiley and Sons
Year
1988
Tongue
German
Weight
451 KB
Volume
71
Category
Article
ISSN
0018-019X

No coin nor oath required. For personal study only.

✦ Synopsis

The preferred conformation of the acetoxyphenyl fragment shows a planar acetoxy (AcO) group perpendicular to the Ph ring. Steric hindrance strongly limits and affects rotation about the C-OCOCH, bond: if the AcO group twists away from its perpendicular conformation, the carbonyl oxygen moves to keep the nonbonded distance to the atoms in ortho-position maximal. This is achieved by some twisting about the 0-COCH, bond correlated with angle bending at the @so-C-atom and ester 0-atom. The maximum observed deviation away from the perpendicular conformation is -47". In the case of one or two ortho-hydrogens, deviations of the AcO group from the perpendicular conformation tend to be larger than in the case of two substituents.

📜 SIMILAR VOLUMES

Conformational Flexibility of the Methox
Conformational Flexibility of the Methoxyphenyl Group Studied by Statistical Analysis of Crystal Structure Data
✍ Wolfgang Hummel; Karel Huml; Hans-Beat Bürgi 📂 Article 📅 1988 🏛 John Wiley and Sons 🌐 German ⚖ 621 KB

In a large sample of observed methoxyphenyl groups, the twist angle 7 about the Me0 -Cph bond measuring internal rotation of the Me0 group shows a continuous distribution with maxima at 0" (coplanar conformation) and -90" (perpendicular conformation). The preferred conformation of methoxyphenyl depe

ToBaD: A method for the estimation of to
ToBaD: A method for the estimation of torsion barriers from crystal structure data; conformational analysis of N,N-dimethylaniline and derivatives
✍ M. L. Verdonk; R. W. Tjerkstra; I. S. Ridder; J. A. Kanters; J. Kroon; W. J. M. 📂 Article 📅 1994 🏛 John Wiley and Sons 🌐 English ⚖ 561 KB

## Abstract A new method for the estimation of torsion barriers and its application to conformational analysis is presented. This method, the ToBaD method (method of the torsion barrier derivative), makes use of crystal structure data. It is based on the assumption that the conformation of a compou

Geometry and Conformation of the α-Amino
Geometry and Conformation of the α-Aminoisobutyric Acid Residue in Simple Derivatives and Dipeptides. Four New X-ray Structural Analyses and a Statistical Analysis from Known Crystal Data
✍ Valle, Giovanni ;Crisma, Marco ;Formaggio, Fernando ;Toniolo, Claudio ;Jung, Gün 📂 Article 📅 1987 🏛 John Wiley and Sons 🌐 English ⚖ 673 KB

The results of X-ray diffraction analyses on two m-aminoisobutyric acid (Aibl derivativcs, methyl u-(acetylamino)isobuknoate (Ac-Aib-OMc. I ) and bcnzyl a-[(beazyloxycarbonyl)arnino]isobutanoate (2-Aib-OBA, 2), and two terminally blocked, Aib-conlining dipcptides, methyl cr-[(acctyl-~-alanyl)nmino]i