Annonin I ( 1) and anonin VI ( 9) were isolated from the seeds of ANNONA SQUAMOSA L. (Annonaceae). The constitution of 1 is identical with that of squamocin, isolated by Fujimoto et al. (8). The relative configuration of 1 was elucidated by X-ray diffraction analysis of a derivative. The constitution and relative configuration of 9 was established by (13)C- and (1)H-NMR spectroscopy using data of derivatives.

Abstract:The substance under investigation is taken as a model for hard segments consisting of MDF) and 1,4-butane diamine. It crystallizes in the triclinic space group P I with a = 4.6297; b = 5.8259; c = 25.286 A; c~ = 90.721; ~ = 91.580; y = 102.90 degrees and Z = 1. Bond distances and angles are given, together with some data on the conformation.The most significant finding is that neighbouring molecules in one and the same plane are linked to one another by means of bifurcated hydrogen bonds.A comparison with the corresponding data for an analogous bis-urethane provides a plausible explanation of the main differences between diamine and glycol extension in polyurethane elastomers.

The diastereoselective total synthesis of the naturally occurring hepatoprotective agent clausenamide (3hydroxy-5-(a-hydroxybenzyl)-l-methyl-4-phenylpyrrolidin-2-one) is described, starting from ethyl cinnamate and diethyl acetamidomalonate. The enantioselective total synthesis of optically pure (+)-clausenamide is presented. The synthesis is based on a novel method for the preparation of optically pure (2S,3S)-3-phenylglutamic acid.

The active (-) enantiomer of amlodipine was originally reported to have R configuration. This does not concur with other 1,4-dihydropyridines with known absolute configuration. This configuration has now been determined by X-ray structural analysis using (1S)-camphanic acid and (S)-2-methoxy-2-phenylethanol as chiral probes. Both determinations gave the S configuration for the amlodipine (-) enantiomer with the greater Ca-antagonistic activity.

Single‐crystal x‐ray diffraction analysis is performed on a model compound (bisurethane of diphenylmethane‐4–monoisocyanate and butanediol‐1,4) for the thermoplastic polyurethane (TPU) hard segment formed from diphenylmethane‐4,4′‐diisocyanate and butanediol‐1,4. The resulting structure is compared to structure models of corresponding TPU hard segments, especially to the structure proposed by Blackwell and Ross. Our results confirm this structure model showing a planar zigzag of the (CH2)4 group and planar hydrogen bonding between the urethane groups of adjacent molecules. X‐ray diffraction analyses of polymeric TPU hard segments and of TPU elastomers with noncrystallizing soft segments lead to a revision of the dimensions of the proposed lattice cell, resulting in a more plausible value of 1.3226g/cm3 for the crystal density.