1,3-Dithiane is used in umpolung reactions such as the Corey-Seebach reaction. It acts as a reagent for the deoxygenation of sulfoxides to their corresponding sulfides. Further, it is used as a protecting group for carbonyl compounds used in organic synthesis. It serves as a useful labeled synthon. In addition to this, it is used in the preparation of 2-ethyl-[1,3]dithiane.
The 2-lithio derivative, normally generated with n-BuLi, behaves as a formyl anion equivalent. It has been shown that the rigorous exclusion of atmospheric oxygen minimizes side reactions and is critical in obtaining optimum results in these lithiation procedures: J. Org. Chem., 60, 4258 (1995).
Monoalkylation of the 2-lithio-derivative and cleavage of the dithiane leads to an aldehyde. Successive dialkylation provides a route to ketones. For reviews of the reversal of the normal reactivity of groups, "umpolung", see: Angew. Chem. Int. Ed., 18, 239 (1979), and of the umpolung of carbonyl activity through sulfur-containing reagents: Synthesis, 357 (1977). See also 1,3-Propanedithiol, A15261, 1,3-Dithiolane, L11914, and 1,2-Ethanedithiol, L12865.
For an example of successive acylation and alkylation of 1,3-dithiane, which can be carried out as a one-pot sequence, see: Synthesis, 625 (1980).
Reaction with 2-cyclohexenone proceeds via 1,2-addition. For details of this and subsequent cleavage and rearrangement, see: Org. Synth. Coll., 8, 309 (1993):
Cleavage of 1,3-dithianes has been effected by a variety of methods, including:
Chloramine-T: Synth. Commun., 2, 7 (1972); NCS, AgNO3, acetonitrile-water: J. Org. Chem., 36, 3553 (1971); 48, 1552 (1983); SO2Cl2, silica, DCM-water: Synthesis, 678 (1976); Bromodimethylsulfonium bromide (from DMSO and bromine): Synthesis, 720 (1979); DMSO-HCl-dioxane: Synthesis, 679 (1982); CuCl2, CuO, acetone: Org. Synth. Coll., 6, 109 (1988); CAN, acetonitrile-water: Synth. Commun., 11, 423 (1981); DDQ, acetonitrile-water: J. Chem. Soc., Perkin 1, 453 (1996); Phenyl phosphorodichloridate, NaI, acetonitrile-DMF: Tetrahedron Lett., 29, 5471 (1988); Glyoxylic acid in AcOH: Synthesis, 694 (1976); HIO4, THF-ether: Tetrahedron Lett., 37, 4331 (1996); PhI(OAc)2, acetone-water: Syn. Commun., 30, 4081 (2000). For facilitation of cleavage of 1,3-dithianes by S-alkylation, see Trimethyloxonium tetrafluoroborate, A15175.
For conversion to the dithienium salt by hydride abstraction, see Triphenylcarbenium tetrafluoroborate, A12949.
Reviews: Synthetic uses of 1,3-dithianes: Tetrahedron, 45, 7643 (1989); Chemistry of 1,3-dithioacetals: Organosulfur Chemistry, P. Page, Ed., Academic Press N.Y. (1995).
Unoh, Y.; Hirano, K.; Satoh, T.; Miura, M. Rhodium(III)-Catalyzed Oxidative Alkenylation of 1,3-Dithiane-Protected Arenecarbaldehydes via Regioselective C-H Bond Cleavage. Org. Lett. 2015, 17 (3), 704-707.
Oksdath-Mansilla, G.; Hajj, V.; Andrada, D. M.; Argu?ello, J. E.; Bonin, J.; Robert, M.; Peñéñory, A. B. Photoremoval of Protecting Groups: Mechanistic Aspects of 1,3-Dithiane Conversion to a Carbonyl Group. J. Org. Chem. 2015, 80 (5), 2733-2739.