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11.
Adimulam Chandra Shekhar Akula Ravi Kumar Gangaram Sathaiah Kengiri Raju Pamulaparthy Shanthan Rao Madabhushi Sridhar Banda Narsaiah Punnamraju Venkata Satya Surya Srinivas Balasubramanian Sridhar 《Helvetica chimica acta》2012,95(3):502-508
A facile heterogeneous synthesis of 3‐amino‐1‐aryl‐1H‐naphtho[2,1‐b]pyran and 2‐amino‐4‐aryl‐4H‐1‐benzopyran derivatives 3 and 5 , respectively, was carried out efficiently by one‐pot three‐component coupling of an aromatic aldehyde 1 , an active methylene compound 2 , and naphthalen‐2‐ol or a phenol 4 in the presence of 5‐Å molecular sieves under solvent‐free microwave‐irradiation conditions (Scheme 1 and 2, Tables 1 and 2). The catalyst was recovered and recycled (Table 3). 相似文献
12.
Functionalized chromanes were prepared by sequential ‘[3+3]-cyclization/Williamson’ reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 1,1,3,3-tetramethoxypropane, 3-silyloxyalk-2-en-1-ones, and 1,1-diacetylcyclopropane. The first step of the sequence involves [3+3] cyclizations of the starting materials to give 2-(3-chloropropyl)phenols. The subsequent cyclization proceeds by intramolecular nucleophilic substitution. 6-(2-Hydroxybenzoyl)chromanes were prepared based on sequential ‘[3+3]-cyclization/Williamson’ reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 3-formylchromones. 相似文献
13.
Samaresh Jana 《Tetrahedron letters》2006,47(33):5949-5951
Aromatic carbonyl compounds undergo smooth intramolecular radical cyclization with alkenes or alkynes using titanocene(III) chloride to furnish the corresponding benzopyrans. The radical initiator, Cp2TiCl, was prepared in situ from commercially available titanocene dichloride (Cp2TiCl2) and zinc dust in THF under argon. 相似文献
14.
Two new flavanones, tonkinochromanes A ( 1 ) and B ( 2 ), and a new chalcone, tonkinochromane C ( 3 ), were isolated from the roots and rhizomes of Sophora tonkinensis. Their structures were elucidated by spectroscopic methods including 2D‐NMR and MS experiments. Of the three isoprenyl substituents in these compounds on rings A and B, one to two were found to be ring‐fused in the form of either dihydro‐ or regular 2,2‐dimethyl‐2H‐pyran moieties. 相似文献