Study On The Ring-opening Reaction Of Five And Six-membered Non-tensioning Ring

Organic chemists have always focused on the exploration and development of new methods for organic synthesis.The ring-opening and transformation reactions of cyclic compounds occupy a very important position in the synthesis of natural products and pharmaceutical intermediates.In the past decades,the ring-opening reactions of tensile rings,such as three-membered rings and four-membered rings,have been extensively and deeply studied.However,some of the more stable non-strength ring compounds that are used in organic synthesis have slowly entered the chemist's field of vision,but their research progress is somewhat lagged behind the ring-opening reaction of the tensile rings.Based on this,this paper explores the ring-opening reactions of several stable nontensile ring compounds and the transformation reactions of the products after ring opening.The 4-chromanone and ethanol had rapidly and efficiently undergo ring-opening reaction at room temperature with the aid of sodium hydroxide.The ring-opening products participated nucleophilic substitution reaction with variously substituted indoles with the Lewis acid BF₃.Et₂O as catalyst,and obtained the 1-?2-hydroxyphenyl?-3-?1H-indol-3-yl?propan-1-one.Other nucleophilic reagents based on carbon,thio,and nitrogen can also underwent nucleophilic substitution reaction with ring-opening products 4-chromanone under the same catalyst,BF₃.Et₂O.In the case of a solvent composed of ethanol and acetonitrile 1:1 volume ratio,1-?2-hydroxyphenyl?-3-?1H-indol-3-yl?propan-1-one could be directly synthesized from 4-chromanone and indole through one-pot two step reaction under the catalysis of sodium hydroxide and boron trifluoride etherate respectively.The reaction of 4-chromanone and 1,3-dicarbonyl compounds could give aryl-substituted cyclohexene under base condition.The ring-opened products of 4-chromanone could also reactwithelectron-richanilinetosynthesizearyl-substitutedquinoline.1-?2-hydroxyphenyl?-5-phenylpentane-1,5-dione,a ring-opening transformation product of 4-chromanone,has been reacted with?-bromoacetophenone to give polysubstituted benzofurans.which can also react with 3-formyl-4-chlorocoumarin smoothly to synthesize chromeno-2,6,9-trioxabicyclo-[3.3.1]nonadienes scaffolds.Vv A three-component reaction of o-aminobenzaldehyde,2-methylindole and variously ketones with Lewis acid boron trifluoride etherate as catalyst directly synthesized quinoline-fused 1-benzazepine derivatives.The C,N-1,6-bisnucleophile generated in situ through an indole-to-quinoline transformation is the key intermediate that ensure the three-component reaction take place.This novel 1,6-C,N-bisnucleophile reacted with variously ketone carbonyl-containing compounds under acid catalyst to give quinoline-fused 1-benzoazepine derivatives.As a substrate with multiple reaction sites,levulinic acid participated in the multi-functional reaction with o-aminobenzaldehyde and2-methylindole to give more complex benzoazepine derivatives.Various aromatic aldehydes also have been used as electrophiles to react with these prepared C,N-1,6-bisnucleophiles to synthesize the corresponding benzoazepine derivatives,which greatly enriched the diversity of benzoazepine derivatives.