Three-component coupling using arynes and DMF: straightforward access to coumarins via ortho-quinone methides.
نویسندگان
چکیده
ortho-Quinone methides, arising from a formal [2+2] cycloaddition between arynes and DMF, were found to facilely undergo a [4+2] cycloaddition with ester enolates or ketenimine anions to produce diverse coumarins in a straightforward manner.
منابع مشابه
Three-component coupling reactions of arynes for the synthesis of benzofurans and coumarins.
The domino three-component coupling reaction of arynes with DMF and active methylenes or methines was studied as a highly efficient method for preparing heterocycles. Coumarin derivative 5 was formed when diethyl malonate (2) or α-bromomalonate (3) were used as a C2-unit. In contrast, dihydrobenzofurans 7a and 7b were obtained by using α-chloroenolates generated from α-chloromalonates 4a and 4b...
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We disclose herein a highly enantioselective protocol for the Brønsted acid-catalyzed addition of indoles and phenols to in situ-generated ortho-quinone methides which deliver broadly substituted diarylindolylmethanes and triarylmethanes, respectively, in a one-pot reaction under very mild conditions. A chiral phosphoric acid catalyst has been developed for this process serving to convert the s...
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A bifunctional squaramide-catalyzed reaction of azlactones with o-quinone methides in situ generated from 2-(1-tosylalkyl)-phenols has been successfully developed under basic conditions, providing an efficient and mild access to chiral dihydrocoumarins bearing adjacent tertiary and quaternary stereogenic centers in high yields with excellent diastereo- and enantioselectivities.
متن کاملCatalytic Asymmetric Intramolecular [4+2] Cycloaddition of In Situ Generated ortho-Quinone Methides.
Herein, we describe the first catalytic asymmetric intramolecular [4+2] cycloaddition of in situ generated ortho-quinone methides. In the presence of a confined chiral imidodiphosphoric acid catalyst, various salicylaldehydes react with dienyl alcohols to give transient ortho-quinone methide intermediates, which undergo an intramolecular [4+2] cycloaddition to provide highly functionalized fura...
متن کاملortho-Quinone methides from para-quinones: total synthesis of rubioncolin B.
A concise synthesis of rubioncolin B is described, which features an unprecedented intramolecular Diels-Alder reaction involving an ortho-quinone methide and a naphthofuran moiety. The ortho-quinone methide is generated through a surprisingly facile tautomerization of a para-quinone.
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ورودعنوان ژورنال:
- Chemical communications
دوره 47 30 شماره
صفحات -
تاریخ انتشار 2011