Vinyl-substituted (Z)-stilbenes are stereoselectively synthesised on treatment of 4-arylbuta-2,3-dien-1-ols with arylboronic acids in the presence of a rhodium(I) catalyst. The reaction proceeds through the regioselective addition of organorhodium(I) species across the aryl-substituted carbon–carbon double bond of the allene moiety and subsequent δ-elimination of Rh(I)–OH.
Facile synthesis of multisubstituted buta-1,3-dienes via Suzuki–Miyaura and Kumada cross-coupling strategy of 2,4-diiodo-buta-1-enes with arylboronic acids and Grignard reagents
作者:Li-Xiong Shao、Min Shi
DOI:10.1039/b504071j
日期:——
One-pot SuzukiâMiyaura-type and Kumada-type cross-coupling reactions of 2,4-diiodo-buta-1-enes with arylboronic acids and alkyl/aryl magnesium bromides were carried out in the presence of accessibly simple catalysts under mild conditions. As a result, some 1,1,2-trisubstituted buta-1,3-dienes were obtained including the Tamoxifen-type, which have potential adjuvant therapy in women who have suffered from breast cancer and cyclooxygenase-2-type (COX-2-type) inhibitors, some of which have been proved to elicit efficient anti-inflammatory analgesic activities and less adverse gastrointestinal side effects and to be very useful in the prophylactic treatment of a wide variety of cancers and neurodegenerative disorders.
Reactions of Styrylmalonates with Aromatic Aldehydes: Detailed Synthetic and Mechanistic Studies
作者:Denis D. Borisov、Roman A. Novikov、Yury V. Tomilov
DOI:10.1021/acs.joc.0c02891
日期:2021.3.19
Reactions of styrylmalonates with aromaticaldehydes in the presence of Lewis and Brønsted acids and their regularities have been studied in detail. Approaches to the synthesis of various polysubstituted 5,6-dihydropyran-2-ones, indenes, aryl-containing dienes and trienes, cyclopentadienes, and polycyclic lactones have been developed with chemo-, regio-, stereo-, and diastereoselectivity control. The
Z- as well as E-isomers of 1,2-diarylbutadienes undergo Diels-Alder reactions with nitrosobenzenes regiospecifically, but the adducts have different structures (3 or 4, respectively) in both cases. From kinetic results it is concluded that the somewhat anomalous cycloaddition of the E-isomers is facilitated and directed by the intermediate formation of a CT-complex.