1,2-Oxathianes, stereochemistry

Also, the reaction pathways of the Corey-Chaykovsky epoxidation reaction have been compared quantum-chemically <1999JOC4596>. As models for one transition state, 1,3-oxathiane compounds such as 52, suitably substituted to allow comparison with experiment (Equation 3), were calculated and these predicted both the absolute stereochemistry of the main product 53 and the distribution of the other stereoisomers, as supported by experimental results. Thus, this theoretical study was able to identify the transition state which proved to be responsible for the stereoselectivity of the catalytic Corey-Chaykovsky epoxidation reaction. 

Grosu and co-workers also studied the complex configurational and conformational aspects of the unique stereochemistry of substituted spiro-l,3-oxathiane derivatives 100-102 by NMR spectroscopy <2001T8751>. 

The complete NMR analysis of the bicyclic decalin-like bis-l,3-oxathiane 107 revealed the t-position of 1,5-dioxa-3,7-dithiadecalin, the equatorial position of the phenyl substituents, and the axial orientation of the R substituent at the same skeletal position <20040121 >. By the same methods, the stereochemistry of the spiro analog 108 was clarified <1998C267>. 

The stereochemistry of a few substituted 1,2-oxathianes 77-79, freshly synthesized (98TL1251), was studied (cf. Scheme 28) the conformation of the substituents at the six-membered ring is in agreement with NOE enhancements and the characteristic ax I ax vs. ax/equ and equ/equ vicinal... 

The stereochemistry, physical and chemical properties and some transformations of 1,3-oxathianes, especially alkyl substituent effects on the preferred conformers, were reviewed (99MI73, 00MI17). Also 1,3-oxathiane and its 2-substituted homologs were theoretically calculated using the semiempirical AMI and PM3 methods (98MI14) the experimental parameters are adequately reproduced. In the case of 5-alkyl substituted... 

The methods of synthesis, the configurational and conformational aspects of the stereochemistry and the main spectral properties and reactions of 1,3-oxathiane derivatives were reviewed after submitting the manuscript (2003H1477). 

A series of polyspiro-l,3-oxathianes has been synthesised from the condensation of a 1,3-mercaptoalcohol with a diketone (Scheme 30) and their stereochemistries have been... 

The conformations of isomers of 2,6-dichloro-l,4-oxathian have been determined from C—H spin-spin coupling constants.When 6-methyl-1,4-oxathian-2-one was ethylated, equal amounts of cis- and trart5-4-ethyl-6-methyl-2-oxo-l,4-oxathianium salts were formed. Several related compounds were synthesized, and their stereochemistry was studied.A new hydroborating agent, borane-oxathian (309), has several advantages over others for example, it is stable, moderately soluble in water, and has less odour than others. Its... 

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