93254-81-0Relevant articles and documents
Synthesis of Benzodihydrofurans by Asymmetric C?H Insertion Reactions of Donor/Donor Rhodium Carbenes
Lamb, Kellan N.,Squitieri, Richard A.,Chintala, Srinivasa R.,Kwong, Ada J.,Balmond, Edward I.,Soldi, Cristian,Dmitrenko, Olga,Casti?eira Reis, Marta,Chung, Ryan,Addison, J. Bennett,Fettinger, James C.,Hein, Jason E.,Tantillo, Dean J.,Fox, Joseph M.,Shaw, Jared T.
supporting information, p. 11843 - 11855 (2017/09/07)
Metal carbenes appended with two electron-donating groups, known as “donor/donor” carbenes, undergo diastereo- and enantioselective rhodium-catalyzed C?H insertion reactions with ether substrates to form benzodihydrofurans. Unlike the reactions of metal carbenes with electron-withdrawing groups attached, the attenuated electrophilicity enables these reactions to be conducted in Lewis basic solvents (e.g., acetonitrile) and in the presence of water. The diazo precursors for these species are prepared in situ from hydrazone using a mild and chemoselective oxidant (MnO2). Although this sequence often can be performed in one-pot, control experiments have elucidated why a “two-pot” process is often more efficient. A thorough screening of achiral catalysts demonstrated that sterically encumbered catalysts are optimal for diastereoselective reactions. Although efficient insertion into allylic and propargylic C?H bonds is observed, competing dipolar cycloaddition processes are noted for some substrates. The full substrate scope of this useful method of benzodihydrofuran synthesis, mechanisms of side reactions, and computational support for the origins of stereoselectivity are described.
Asymmetric synthesis of 3,4-dihydrocoumarins by rhodium-catalyzed reaction of 3-(2-hydroxyphenyl)cyclobutanones
Matsuda, Takanori,Shigeno, Masanori,Murakami, Masahiro
, p. 12086 - 12087 (2008/04/11)
3,4-Dihydrocoumarin derivatives were synthesized in a highly enantioselective manner from 3-(2-hydroxyphenyl)cyclobutanones through enantioselective carbon-carbon bond cleavage. A cascade reaction with electron-deficient alkenes introduced a carbon-carbon
Photocyclization Reactions. Part 5 [1]. Synthesis of Dihydrobenzofuranols Using Photocyclization of 2-Alkoxybenzophenones and Ethyl 2-Benzoylphenoxyacetates
Sharshira, Essam Mohamed,Shimada, Satoru,Okamura, Mutsuo,Hasegawa, Eietsu,Horaguchi, Takaaki
, p. 1797 - 1805 (2007/10/03)
Photocyclization reactions were carried out on 2-alkoxybenzophenones 1a-h and ethyl 2-benzoylphenoxyacetates 2a-e in acetonitrile. Irradiation of 1a-h gave dihydrobenzofuranols 4a-h in 68-84% yields. Similarly, irradiation of 2a-e afforded dihydrobenzofuranols 8a-e in 72-75% yields. Ethyl acrylates 9b-c were also produced in 6-8% yields from photoreactions of 2b-c. Substituent effects on cyclization of 1,5-biradical intermediates and reaction pathways are discussed. Benzophenones are useful compounds to prepare dihydrobenzofuranols by photocyclization.
