Photoinduced molecular transformations. 140. New one-step general synthesis of naphtho[2,3-b]furan-4,9-diones and their 2,3-dihydro derivatives by the regioselective [3 + 2] photoaddition of 2-hydroxy-1,4-naphthoquinones with various alkynes and alkenes: application of the photoaddition to a two-step synthesis of maturinone
摘要:
2,3-Dihydronaphtho[2,3-b]furan-4,9-diones can now be produced in one step in 41-83% yields by an unprecedented regioselective [3 + 2] photoaddition of 2-hydroxy-1,4-naphthoquinones with a variety of alkenes. The dihydronaphthofurandiones can be readily transformed into naphtho[2,3-b]furan-4,9-diones. This new photoaddition reaction has been successfully applied to a two-step synthesis of maturinone, a constituent of Cacalia decomposita A Gray. Naphtho[2,3-b]furan-4,9-diones can also be obtained directly by a new [3 + 2] photoaddition of 2-hydroxy-1,4-naphthoquinone with various alkynes in acetone. The photoaddition between 2-hydroxy-1,4-naphthoquinones and alkenes in acetone involves an initial formation of furanohydroquinones, which are oxidized to furanoquinones. A quenching experiment together with the regioselective nature of photoaddition indicate that the photoaddition is a two-step process from a triplet of excited quinones and involves more stabilized polar biradicals or ionic intermediates generated from them by an intramolecular electron transfer from which the furanohydroquinones are formed.
The 3+2-type cycloaddition reaction of 2-hydroxy-1,4-naphthoquinones with various alkenes or phenylacetylene was mediated by ammonium cerium(IV) nitrate (CAN) to give the corresponding naphtho[2,3-b]furan-4,9-dione and naphtho[1,2-b]furan-4,5-dione derivatives. The reaction of 2-hydroxy-1,4-benzoquinones with alkenes in the presence of CAN similarly proceeded to give benzofuran-4,7-dione and benzofuran-4,5-dione derivatives. 3-Hydroxy-1H-phenalen-1-one also underwent the CAN-mediated cycloaddition with alkenes or phenylacetylene to give the corresponding 7H-phenaleno[1,2-b]furan-7-one derivatives.
Photoinduced molecular transformations. Part 120. New one-step general synthesis of 2,3-dihydronaphtho[2,3-b]-furan-4,9-diones by regioselective photoaddition of 2-hydroxy-1,4-naphthoquinones with various alkenes and its application to a two-step synthesis of maturinone
A one-step formation of 2,3-dihydronaphtho-[2,3-b]furan-4,9-diones in 41-83% by a new 2 + 3 type regioselective photoaddition of 2-hydroxy-1,4-naphthoquinones with a variety of alkenes is reported. The dihydronaphthofurandiones can readily be transformed into naphtho[2,3-b]furan-4,9-diones including a natural quinone, maurinone.
KOBAYASHI, KAZUHIRO;SHIMIZU, HIDEKI;SASAKI, AKIYOSHI;SUGINOME, HIROSHI, J. ORG. CHEM., 56,(1991) N, C. 3204-3205