2,3-dichloro-l,4-dioxane

Bob Ardrey obtained a first degree in Chemistry from the University of Surrey where he went on to obtain his doctorate stndying the chemistry of trans-2,3-dichloro-l,4-dioxan and the stereochemistry of its reaction prodncts using primarily mass spectrometry and nnclear magnetic resonance spectroscopy. He then carried ont post-doctoral research at King s College, London, into the development of emitters for field-desorption mass spectrometry. 

Dichloro-l,4-dioxane and 2,3-dibromo-l,4-dithiane react smoothly with tin dithiolates 95 in the presence of BF3 Et20 to give the corresponding tricyclic adducts 96 as single m-diastereoisomers in good yields <1998JOC3952>. 

Synthesis of 2,3-dihydro-l,4-dithiin 11 was accomplished from l,3-dithiol-2-one 247 in the presence of dibro-moethane and potassium hydroxide <1998JOG3952>, while reaction of 2,3-dichloro-l,4-dioxane with powdered Zn in hexamethylphosphoramide (HMPA) was used for the synthesis of 1,4-dioxene 10 <1998JPP10067773>. To obtain substituted 1,4-oxathianes, the hydrogenation of the corresponding partially saturated compounds has been employed <2001J(P1)2604>. 

Dichloro-l,4-dioxane, trans- 1,4-Dioxane, 2,3-dichloro-, trans- (3883-43-0), 65, 68... 

Dichloro- and -diphenyl-1,4-dioxan The so-called cis 2,3-dichloro-l,4-dioxan, m.p. 52°, is actually the irtms-isomer the 2,3-diphenyl-l,4-dioxans with m.ps. 46° and 132° should be designated cis and trans respectively the dioxan ring has a chair conformation throughout Chen and Le Ffevre, 1965... 

In Fig. 2.13 the electronic distributions in chloromethoxymethane 33 and in the partial structure of cw-2,3-dichloro-l,4-dioxane 32 are compared. 

Altona C (1964) Ph.D. thesis, Leiden Altona C, Romers C (1963) The conformation of non-aromatic ring compounds. VIII. The crystal structure of cis-2,3-dichloro-l,4-dioxane at -140 °C. ActaCryst 16 1225-1232... 

It is believed that equatorial substituents such as chlorine or bromine would increase the guest diameter beyond the allowed values (assuming that the guest molecules stack roughly parallel to the canal ). Support for this comes from the study of fluorocyclohexane where the population of the axial conformer is not enhanced to any major extent . Nitro- and cyano-cyclohexane, rrons-l,2-dichloro-, trans-1,2-dibromo-, tmns-1,4-dichloro-, irons-1,4-dibromo-, and irons-l-bromo-4-chloro-cyclohexane all pack most efficiently in the thiourea canals as the axial or diaxial conformer . rrons-2,3-dichloro-l,4-dioxane behaves similarly . In contrast isocyanato-, Irons-1,4-diiodo-, irons-l-bromo-4-iodo-, and irons-l-chloro-4-iodo-cyclohexane are present as mixtures of the axial/equatorial or diaxial/diequatorial conformations as appropriate The reason for this anomalous behaviour of the iodosubstituted cyclohexanes is not clear. 

A compound isolated from the reaction of /m/tr-2,3-dichloro-l, 4-dioxan with concentrated sulphuric acid has been shown to be (223). No stereochemistry could be assigned. ... 

Halogen atoms in 1,4-dioxane prefer to occupy an axial position, favored by an anomeric effect For this reason, trans-2,3-dichloro-l,4-dioxane prefers the diaxial geometry 1 ... 

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