2-Trimethylsilyl-1,3-dithiane is the precursor of dithioketene acetals which are good substrates for
both cationic and anionic cyclization processes; the anion reacts with unsaturated ketones and aldehydes to give vinyl dithioketene acetals that can be used as dienes or for the preparation of substituted α,β-unsaturated alkyl ketones; alkylation of the anion provides a general synthesis of acylsilanes. It participates the following reactions: Thioketene Acetals, Cationic and Anionic Cyclizations, Unsaturated Dithioketene Acetals, Acylsilanes, Multicomponent Linchpin Reactions, Formation of Bis(acylsilanes) etc.
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2-Trimethylsilyl-1,3-dithiane is prepared by alkylation of 2-lithio-1,3-
dithiane with chlorotrimethylsilane (eq 1).
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2-(Trimethylsilyl)-1,3-dithiane participates in Lewis base-catalyzed 1,3-dithiane addition to electrophiles such as carbonyl compounds and N-substituted aldimines. It undergoes novel diazo transfer reaction with tosyl azide in hexamethylphosphoramide-THF to yield 2-diazo-1,3-dithiane, which on decomposition yields formal carbene adducts. It is a versatile acyl anion equivalent.
Purification Methods
Fractionally distil the dithiane through an efficient column and collect the fractions that have the correct NMR and IR spectra. 1H NMR (CCl4) 6.36 (SiMe3), 9.87 (SCHS) and dithiane H at 7 and 8 (ratio 1:9:4:2) from Me4Si; UV 244nm ( 711), sh 227nm ( 800). [Corey et al. J Am Chem Soc 89 max 434 1967.]
