No abstract

General, high-yield metathesis reactions provide two related and comprehensive series of dithiabismuth heterocycles. The compounds are characterized by spectroscopic and X-ray crystallographic analysis. Monocycles 4), and 2-chloro-1,3-dithia-6-oxa-2-bismocane (5) are kinetically stable with respect to the tethered bicyclic derivatives 1,2-bis((1,3-dithia-2-bismolan-2-yl)thio)ethane ( 6), 1,3-bis((1,3-dithia-2-bisman-2yl)thio)propane ( 7), 1,4-bis((1,3-dithia-2-bismepan-2-yl)thio)butane (8), bis((1,3,6-trithia-2-bismocan-2-yl)thio)ethyl) sulfide ( 9), and bis(((1,3-dithia-6-oxa-2-bismocan-2-yl)thio)ethyl) ether (10). Mass spectrometry provides an excellent means of characterization of compounds of this nature and is responsible for the identification of monocyclic bismuthenium cations as general and dominant dissociation products. In addition, the atmospheric pressure chemical ionization technique reveals solvent coordination chemistry of the bismuthenium cations.

New carotenoids, cryptocapsin-5,6-epoxide, 3′-deoxycapsanthin-5,6-epoxide, and cryptocapsin-5,8-epoxides, have been isolated from the ripe fruits of red mamey (Pouteria sapota). Cryptocapsin-5,6-epoxide was prepared by partial synthesis via epoxidation of cryptocapsin, and the (5R,6S)- and (5S,6R)-stereoisomers were identified by HPLC-ECD analysis. Spectroscopic data of the natural (anti) and semisynthetic (syn) derivatives obtained by acid-catalyzed rearrangement of cryptocapsin-5,8-epoxide stereoisomers were compared for structural elucidation. Chiral HPLC separation of natural and semisynthetic samples of cryptocapsin-5,8-epoxides was performed, and HPLC-ECD analysis allowed configurational assignment of the separated stereoisomers.

Carotenoids are substantially hydrophobic antioxidants. Hydrophobicity is this context is rather a disadvantage, because their utilization in medicine as antioxidants or in food chemistry as colorants would require some water dispersibility for their effective uptake or use in many other ways. In the past 15 years several attempts were made to synthetize partially hydrophilic carotenoids. This review compiles the recently synthetized hydrophilic carotenoid derivatives.

From the ripe fruits of red mamey (Pouteria sapota) sapotexanthin, a new carotenoid, was identified as (all-E,5'R)-β,κ-caroten-6'-one.