Pentaspiranes and hexaspiranes with 1,3-dioxane or 1,3-oxathiane rings: synthesis and stereochemistry
摘要:
The synthesis and stereochemistry of the first reported pentaspiro- and hexaspiro-1,3-dioxane and polyspiro-1,3-oxathiane (from dispiro to hexaspiro) derivatives are described. The crystal structures of a dispiro- and tetraspiro-1,3-oxathiane were determined by X-ray diffraction methods. NMR and chiral column HPLC investigations in solution revealed flexible and semiflexible structures for which syn-anti, cis-trans and d,l isomers were observed. (C) 2004 Elsevier Ltd. All rights reserved.
The synthesis and stereochemistry of the first reported pentaspiro- and hexaspiro-1,3-dioxane and polyspiro-1,3-oxathiane (from dispiro to hexaspiro) derivatives are described. The crystal structures of a dispiro- and tetraspiro-1,3-oxathiane were determined by X-ray diffraction methods. NMR and chiral column HPLC investigations in solution revealed flexible and semiflexible structures for which syn-anti, cis-trans and d,l isomers were observed. (C) 2004 Elsevier Ltd. All rights reserved.
Synthesis of Rodlike Dispiro Hydrocarbon Skeletons for New Liquid Crystal Compounds
A simple synthesis of the dispiro[5.2.5.2]hexadecane skeleton was developed. Starting from the cyclohexanedicarbaldehyde 6 the dispirane was prepared in one step. The synthesised dispirodiketone 4 is a key compound for the preparation of a number of new liquid crystalline compounds, as its linear molecular shape is proved by an x-ray structural analysis of the corresponding diketal 10. Additionally the synthesis of the first dispirane 4 with a [5.2.3.2]-linkage is described.