“…Unlike the aliphatic pentenediols, these cinnamyl alcohols undergo regioselective hydroformylation, as shown by Nozaki et al for the formation of phenyl-substituted tetrahydrofuran-2-ols. Under optimized conditions, the desired cis -2,3,3a,8a-tetrahydrofuro[2,3 b ]benzofuran ( 9a ) is obtained starting from the unsubstituted diol 8a in 69% yield (Scheme ) at 60 °C using the Rh(acac)(CO) 2 /PPh 3 catalyst system with 1,4-dioxane as the solvent. 2 …”
[reaction: see text] Rhodium-catalyzed tandem hydroformylation/acetalization of alpha,omega-alkenediols gives facile access to perhydrofuro[2,3b]furans and perhydrofuro[2,3b]pyrans in good yields. Similarly, benzoannelated tetrahydrofuro[2,3b]furans are obtained by hydroformylation of o-hydroxy cinnamyl alcohols.
“…Unlike the aliphatic pentenediols, these cinnamyl alcohols undergo regioselective hydroformylation, as shown by Nozaki et al for the formation of phenyl-substituted tetrahydrofuran-2-ols. Under optimized conditions, the desired cis -2,3,3a,8a-tetrahydrofuro[2,3 b ]benzofuran ( 9a ) is obtained starting from the unsubstituted diol 8a in 69% yield (Scheme ) at 60 °C using the Rh(acac)(CO) 2 /PPh 3 catalyst system with 1,4-dioxane as the solvent. 2 …”
[reaction: see text] Rhodium-catalyzed tandem hydroformylation/acetalization of alpha,omega-alkenediols gives facile access to perhydrofuro[2,3b]furans and perhydrofuro[2,3b]pyrans in good yields. Similarly, benzoannelated tetrahydrofuro[2,3b]furans are obtained by hydroformylation of o-hydroxy cinnamyl alcohols.
“…A methyl group at the 3-position of the coumarin ring, which was unfavorable in the steric effect to the β-addition, decreased the yield of 3i . The product 3i was obtained as a single diastereomer, and the structure of 3i was explicitly confirmed by X-ray diffraction analysis, whereas a phenyl group at the 3-position resulted in the formation of 3j with a 16:1 diastereomeric ratio in 60% yield, which might be attributed to the stabilized effect to anionic intermediates by the aromatic conjugation and less steric disadvantages by the plane structure. This reaction was sterically sensitive to the substituent at the 4-position of the coumarin, and the formation of 3k was suppressed to give 43% yield.…”
Magnesium-promoted reductive introduction of a trifluoroacetyl group to coumarin in the presence of ethyl trifluoroacetate and the subsequent treatment with trifluoroacetic acid led to simple access to a trifluoromethylated benzofurofuranone at 8a-position with a high regio-and stereoselectivity. Trifluoromethylated or difluoromethylated benzofurofuranone derivatives were also prepared from coumarins including naturally occurring ones only in two successive steps, which might have potential bioactivity in medicinal chemistry.
“…Microminutinin (5) pertains to a class of compounds that displays in vivo activity in the lymphocytic leukemia test system (3)(4)(5), while several other compounds with the benzofuranofuranone unit, e.g., 6 and 7, have anticoagulant activity (6). Furthermore, very recent theoretical studies have revealed that the five-membered rings of the benzofuranofuran derivatives present complex conformational properties (7). The relevant biological and chemical properties render these compounds interesting as synthetic targets.…”
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