Synthetic Study Of Pyrrolnitrin Analogues

Pyrrolnitrin analogues belong to 3,4-disubstituted pyrrole,on which a chloride and asubstituted aryl group are attached to its β-positions.And the synthetic methodology of 3,4-disubstituted pyrrole is less devoloped,how to introduce a substituent to its β-position to prepare 3,4-disubstituted pyrrole is still a great challenge.In recent years,the research of organosilicon compounds has been deepened,and the properties of organosilicon compounds have been applied to organic synthesis.Trimethylsilyl is widely used due to the stabilizing effect(β effect)of carbon ortho ions at the β position in the aryl compounds,so that the transfer reaction of trimethylsilyl is very valuable.At the same time,we found that in the role of N-chlorosuccinimide(NCS)and under the action of protonic acid 3,4-disubstituted pyrrole will occur in two different rearrangement reaction in the experiment.Under the action of NCS,3,4-bis(trimethylsilyl)pyrrole will be rearranged to produce 2,4-bis(trimethylsilyl)pyrrole and 2,4-bis(trimethylsilyl)-3-chloro-pyrrole;Under the action of protonic acid,3,4-bis(trimethylsilyl)pyrrole will be rearranged to produce2,4-bis(trimethylsilyl)pyrrole.We synthesized the raw materials needed for the synthesis of pyrrolnitrin:2-chloro-6-bromoaniline and 3,4-bis(trimethylsilyl)pyrrole.Then,the 3,4-bis(trimethylsilyl)pyrrole was protected by a series of reactions such as the protection of tert butyl carbonate,iodine reaction,Suzuki coupling reaction,in situ chlorination reaction and so on,in the end we synthesized the analogues of pyrrolnitrin.The reaction conditions were optimized,and the synthesis method has the advantages of high reaction conditions and high yield.A series of new compounds were obtained and their structures were determined by NMR spectroscopy.