Intramolecular [4+2] cycloaddition in N-allyl- and N-propargyl-α-furyl lactams
作者:Dmitry S. Poplevin、Eugeniya V. Nikitina、Vladimir P. Zaytsev、Alexey V. Varlamov、Santosh G. Tilve、Fedor I. Zubkov
DOI:10.1007/s10593-018-2290-2
日期:2018.4
The size of nitrogenheterocycle in N-allyl- and N-propargyl-α-furyl lactams, as well as the nature of the unsaturated substituent linked to the nitrogen atom affected the possibility of thermal intramolecular [4+2] cycloaddition between multiple bond and the furan ring. N-Allyl-γ-(α-furyl)butyrolactam was shown to be unreactive at temperatures from 140 to 230°С. Substituted δ-valero- and ε-caprolactams
Reactions between 2-chloromethyl-3-trimethylsilyl-1-propene 1 and N-acyliminium ions, which were generated in situ from α-methoxy or α-acetoxy amides 2, give allylic chlorides 3 in good yields and high stereoselectivities. The allylic chlorides 3 were further transformed to bicyclic methylenepyrrolidines 4 which are building blocks for pharmacologically interesting compounds.
The reaction of N-acyl-alpha-methoxyamines with allyl-, propargyl-, and benzylzinc bromides and Reformatsky reagents proceeds in THF at room temperature. Homoallyl- and homopropargylamines and beta-amino esters are synthesized in good yields.
Photolytic dehydrochlorination of N-chloro-N-alkyl amides: formation of N-(.alpha.-methoxyalkyl) amides