Rh2(OAc)4-catalysed cycloaddition of ethyl diazoacetate (EDA) to 1,2-methylenedioxybenzene 1 gives the corresponding cycloheptatrienes 6 and 7, whereas the reaction of 1,2-dimethoxybenzene 3 affords a new type of stable norcaradiene 9.
Synthesis of α-Tropolones through Autoxidation of Dioxole-Fused Cycloheptatrienes
作者:Alex J. Berkowitz、Ryan P. Murelli
DOI:10.1021/acs.joc.1c02713
日期:2022.4.1
Herein, we describe the formation of tropolones through the autoxidation of Büchner reaction-derived cycloheptatrienes. The reaction is exceptionally simple procedurally, as it involves blowing a stream of compressed air over the cycloheptatriene, and the products can be obtained without any need for chromatography. The chemistry works specifically on dioxolane-fused systems or close variants, and
Regioselective and Enantioselective Intermolecular Buchner Ring Expansions in Flow
作者:Gabrielle S. Fleming、Aaron B. Beeler
DOI:10.1021/acs.orglett.7b02537
日期:2017.10.6
The firstexample of a regioselective and enantioselective intermolecular Buchner ring expansion is reported using continuous flow. The practicality and scope of the reaction are greatly improved under flow conditions. Reactions of ethyl diazoacetate with symmetric and nonsymmetric arenes afford cycloheptatrienes in good yield and excellent regioselectivity. The firstexample of an asymmetric intermolecular
resulted in the formation of 16. Treatment of the endoperoxide 14 with a catalytic amount of triethylamine provided a newisomer of stipitatic acid 11, and 16. Pyrolysis or the CoTPP (TPP = tetraphenylporphyrin) catalyzed reaction of 14 resulted in the formation of iso-stipitatic acid 10, and 18.