Atom Transfer Radical Addition Reaction Of 1,3-dithiane With Alkynes And The Method Of Synthesis Substituted-dithianes

In organic synthesis,radical reaction is one of very important method to construct C-C and C-X bonds.In recent decades,radical reaction with good selectivity controllability has been widely used in organic synthesis.Achieving mild reaction conditions and good regioselectivity is the main direction of radical reactions.In this paper,we studied atom transfer radical addition reaction of 1,3-dithiane with alkynes under mild reaction conditions.Meanwhile,the selective conversion of alkynes with 2-chloro-1,3-dithiane to substituted-dithiane compounds has been demonstrated.This paper is divided in two parts.Firstly,the di-tert-butyl peroxide(DTBP)as an oxidant for atom transfer radical addition reaction of 1,3-dithiane with alkynes has been demonstrated.By optimizing the reaction conditions,we found the optimized reaction conditions:using 2.0 equiv of DTBP in 1,2-dichloroethane leads to ?-chloro-?,?-unsubstued dithianes at room temperature.The reaction mechanism has been studied.The(Z)-?-chloro-?,?-unsaturated dithianes obtained in good yields and high regioselectivities.The reaction has much advantages such as mild conditions,easy to operate,even it can be complete by "one-pot".Secondly,the alcohol mediated reaction of alkynes with 2-chloro-1,3-dithiane to synthesis substituted dithiane compounds has been studied.We has optimized the reaction conditions(methanesulfonic acid and alkyl alcohol).The reaction has good substrate scopes.The reaction has mild conditions,environmentally friendly and without the use of 1,3-propanedithiol.