STUDIES ON THE OXIDATION OF 1,3-DITHIANE AND 5,5-DISUBSTITUTED ANALOGS INCLUDING X-RAY CRYSTAL-STRUCTURE, EQUILIBRATION STUDIES AND PK(A) MEASUREMENTS ON SELECTED OXIDES
Vk. Aggarwal et al., STUDIES ON THE OXIDATION OF 1,3-DITHIANE AND 5,5-DISUBSTITUTED ANALOGS INCLUDING X-RAY CRYSTAL-STRUCTURE, EQUILIBRATION STUDIES AND PK(A) MEASUREMENTS ON SELECTED OXIDES, Journal of the Chemical Society. Perkin transactions. I, (17), 1994, pp. 2363-2368
Oxidation of 1,3-dithiane has been carried out using eight different o
xidants under several different reaction conditions. The most favourab
le conditions for obtaining the required trans-1,3-dithiane 1,3-dioxid
e were to use either MCPBA in Et(2)O or NaIO4 in MeOH-H2O. Other 5,5-d
isubstituted-1,3-dithianes were also prepared and subjected to similar
oxidations. For these compounds the best oxidant for obtaining the tr
ans-dioxides was O-3. A rationalisation for the stereochemical outcome
of the oxidations is presented and requires that trans-1,3-dithiane 1
,3-dioxide is more stable than cis-1,3-dithiane 1,3-dioxide. This is b
orne out by equilibration studies of the two diastereoisomeric sulfoxi
des using N2O4. A rationalisation for the greater stability of the tra
ns compared to the cis isomer is also presented and fits with the pK(a
) values and melting points of the two compounds.