Research On The Reactions Of β-chlorovinyl-1,3-dithianes

Dithiane and its derivatives show important value in natural products and organic synthesis,and participate in many useful functional group conversions.Our group has been long committed in finding and discovering new methods for dithianes derivatives.More recently,we have published the new strategy that alkyne compounds can reacted with 2-chloro-1,3-dithianes in the presence of an oxidizing agent and formed a β-chlorovinyl-1,3-dithianes through a radical mechanism.On this basis,the reactions between β-chlorovinyl-1,3-dithianes compounds and some small molecules such as sodium methoxide,acetylacetone and phenylhydrazine were studied in this thesis.In addition,we have found that the β-chlorovinyl-1,3-dithianes can be converted into β-chloro-α,β-unsaturated aldehydes and β-carbonyl-1,3-dithianes.Further studies also found it can be converted into a vinylidene dithiane intermediates under alkaline conditions followed by a nucleophilic/electrophilic addition reaction.Substituted cyclopentenes and structurally related cyclopentenones serve as key structural components in numerous medicinally important compounds and biologically active molecules.Oh’s group have disclosed the utility of nucleophilic and electrophilic reactivity modes of β-chlorovinyl ketones in the development of novel C-C bond formation reactions.When using dimethyl sulfoxide(DMSO)and acetonitrile as solvent respectively under mild conditions,the regioselective [3+2]-cyclization reactions between β-carbonyl-1,3-dithianes derivatives and unsaturated carbonyl compounds were achieved to allow the direct construction of different substituted cyclopentene structural derivatives.This cyclization has a very good substrate ranges,moderate to good yields and simple operation.Most importantly,the resulting 5-hydroxylated cyclopentene structure requires only a simple NCS-mediated desulfurization process to form a 5-hydroxylated cyclopentenone structure___an important structural motif that is found among biologically active natural products.Additionally,this utility of the methodology provides a good basis for further total synthesis of the natural products.