Catalytic Asymmetric Chlorinative Dearomatization Reaction of Benzofurans

Abstract

Ac atalytic asymmetric chlorinatived earomatization reactiono fb enzofuran derivatives was achieved by using hydroquinidine 1,4-phthalazinediyl diether [(DHQD) 2 PHAL] as the catalyst and Nchlorophthalimide (NCP) as the chlorinating reagent. As eries of chlorinated spiro[benzofuran-2,5'oxazole]s bearing two contiguous stereogenic centers was obtained in high yields( up to 99%) with excellent enantioselectivity (up to 99% ee).

Palladium-Catalyzed Highly Stereoselective Dearomative [3 + 2] Cycloaddition of Nitrobenzofurans

“…[56][57][58] Here, we report a highly stereoselective palladium-catalyzed dearomative [3 + 2] cycloaddition of nitrobenzofurans and nitrobenzothiophenes. 53,[59][60][61][62][63][64]…”

Enantioselective Intermolecular Mannich-Type Interception of Phenolic Oxonium Ylide for the Direct Assembly of Chiral 2,2-Disubstituted Dihydrobenzofurans

“…Therefore, a variety of synthetic methods have been disclosed for the stereoselective construction of this skeleton in recent decades . Especially, there are many effective catalytic approaches for the enantioselective synthesis of chiral DHBs, including [4+1]-cycloaddition, dearomatization of benzofurans, intramolecular carbene C–H/O–H insertion, and others . Despite these efforts, which provide chiral 2,3-dihydrobenzofurans with 2,3- or 3,3-substitutions mainly, the catalytic asymmetric method toward multisubstituted DHBs, especially the 2,2-disusbituted ones, is rare and remains a challenge …”

Recent Dearomatization Strategies of Benzofurans and Benzothiophenes

“…In 2016, You and co‐workers put forth an astonishing methodology [23] for an enantioselective synthesis of a series of 3‐chlorinated spiro[benzofuran‐2,5’‐oxazoles] 82 from benzofuran derivatives 83 using catalytic hydroquinidine‐1,4‐phthalazinediyl diether [(DHQD) 2 PHAL] and a chlorinating agent like N ‐chlorophthalimide (NCP) via chlorinative dearomatization (Scheme 19).…”