Substituent Effects on Regioselectivity of the Diels-Alder Reactions: Reactions of 10-Allyl-1,8-dichloroanthracene with 2-Chloroacrylonitrile, 1-Cyanovinyl Acetate and Phenyl Vinyl Sulfone

Mujeeb A Sultan,Usama Karama

doi:10.1155/2016/3943060

Abstract

Diels-Alder reaction of 10-allyl-1,8-dichloroanthracene (3) with 2-chloroacrylonitrile (4) and 1-cyanovinyl acetate (5) gives exclusively theorthoisomer while its reaction with phenyl vinyl sulfone (10) yields a mixture of two isomeric adducts with priority toorthoisomer. The reactions proceeded under microwave condition in xylene. Configurations of these isomers have been assigned with the help of NMR spectra. The results indicated that the steric effect is dominating toward the isomer regioselectivity in the Diels-Alder reaction of the present compounds.

Highlights

The Diels-Alder reaction is considered one of the most useful synthetic reactions and it is among the most atom economical and reliable carbon-carbon bond forming methods known in organic chemistry [1]
The intermediate 10-allyl-1,8-dichloroanthracene (3) was prepared as described in the literature [20], since allylmagnesium bromide reacted with 4,5-dichloroanthrone (2) which was prepared based on the procedure reported by Goichi et al [21] (Scheme 1)
For C25H20O2SCl2 [M+] 454.0561, Found 454.0543. This is the first study reporting the regioselectivity of the Diels-Alder reaction of 10-allyl-1,8-dichloroanthracene with three different-substituted dienophiles

Summary

Introduction

The Diels-Alder reaction is considered one of the most useful synthetic reactions and it is among the most atom economical and reliable carbon-carbon bond forming methods known in organic chemistry [1]. In this reaction, a conjugated diene the 4π component (diene) reacts with an alkene, the 2π component (dienophile) to build up six-member system. The substituted anthracenes could be interesting targets for the study of regioselectivity and stereoselectivity in the Diels-Alder reactions. The regioselectivity of the Diels-Alder reaction of 10allyl-1,8-dichloroanthracenes (3) with 2-chloroacrylonitrile (4), 1-Cyanovinyl acetate (5), and Phenyl vinyl sulfone (10) has been studied. The structural elucidation of the cycloadducts has been made based on the NMR spectroscopic data

Results and Discussion

Experimental

Conclusion