Synthesis Of Sulfinylated Benzofulvenes And Substituted Pyrroles From 1,3-enynes

Conjugated 1,3-enynes are not only found in many natural products and biologically active molecules,but also very useful intermediates to prepare allenes,carbon rings,heteocycles,and other key structures.Benzofulvenes containing a five-membered carbon ring are known as the key privileged structures of biologically active natural products and pharmaceuticals,and are important molecular subunits in material sciences.On the other hands,pyrrole is an important five-membered nitrogen heterocyclic compound found in many natural products and pharmaceutical molecules with biological activities such as antibacterial,antiviral and antitumour.Therefore,it is of great importance to develop a rapid and efficient method for the construction of benzofulvenes and pyrroles.In this paper,1,3-enyne was used as the starting material for the synthesis of sulfinylated benzofulvenes and bromo-substituted pyrroles,respectively.The main contents are as follows:(1)We have reported the BF₃·Et₂O-promoted cascade cyclization of arylsulfinic acids with 1,3-enynes,and a wide range of sulfinylated benzofulvenes were obtained with good to excellent yields under mild condition.The reaction was carried out in 30minutes at room temperature by using toluene as the solvent.(2)We have developed a method for selective synthesis of bromo-substituted2H-pyrroles and 3H-pyrroles from three-component cascade reactions of 1,3-enynes,TMSN₃ and NBS by controlling the temperature and additive.This method provides a mild,simple and efficient passway for the preparation of functionalized pyrroles.