Access to Electron-Deficient 2,2-Disubstituted Chromanes: A Highly Regioselective One-Pot Synthesis via an Inverse-Electron-Demand [4 + 2] Cycloaddition of <i>ortho</i>-Quinone Methides
We report the one-pot synthesis of 2,2-disubstituted chromanes with electron-withdrawing substituents. This reaction provides a simple yet efficient route to a wide range of electron-deficient chromanes in highyield and excellent regioselectivity. The reaction of salicylaldehyde with 1,1-disubstituted ethylenes smoothly furnishes these electron-deficient chromanes, which can be further transformed
A novel pyridinium salt-supported [hydroxy(tosyloxy)iodo]benzene (HTIB) reagent (N-4-[hydroxy(tosyloxy)iodo]phenyl}pyridinium hexafluorophosphate) was prepared via Zincke’s reaction. The conjugate...
Highly regioselective synthesis of 2,3-disubstituted 2 H -1-benzopyrans: Brønsted acid catalyzed [4+2] cycloaddition reaction with a variety of arylalkynes via ortho -quinone methides
A highly regioselective one-pot synthesis of 2,3-disubstituted-2H-1-benzopyrans has been developed through Brønsted acid catalyzed [4+2] cycloaddition reaction with a variety of arylalkynes via ortho-quinone methides. A catalytic amount of trifluoromethanesulfonic acid effectively promotes the [4+2] cycloaddition reaction of salicylaldehydes with arylalkynes to afford the corresponding 2H-1-benzopyrans
通过布朗斯台德酸通过邻醌醌与各种芳基炔烃进行的[4 + 2]环加成反应,已开发出高度区域选择性的2,3-二取代的2 H -1-苯并吡喃的一锅法合成方法。催化量的三氟甲磺酸有效地促进了水杨醛与芳基炔烃的[4 + 2]环加成反应,以高收率和高区域选择性提供了相应的2 H -1-苯并吡喃。根据试剂,用一些亲核试剂处理环加合物2,3-二苯基-2 H -1-苯并吡喃产生4 H -1-苯并吡喃和2 H -1-苯并吡喃。本反应为官能化的2,3-二取代-2提供了通用途径H -1-苯并吡喃将是合成生物和光化学活性分子的有用工具。
Highly Selective One-Pot Synthesis of Polysubstituted Isoflavanes using Styryl Ethers and Electron-Withdrawing ortho-Quinone Methides Generated In Situ
highly selective one-potsynthesis of polysubstituted isoflavanes has been developed. The reaction proceeds through the cycloaddition of methyl styryl ethers, derived from phenylacetaldehyde dimethyl acetals under acidic conditions, with electron-withdrawing ortho-quinone methides generated in situ. When phenylacetaldehyde dimethyl acetals were reacted with salicylaldehydes, the reaction proceeded smoothly
A novel and convenient approach for tosyloxylation of aromatic ring of some ortho-substituted phenolic compounds using [hydroxy(tosyloxy)iodo]benzene
作者:Om Prakash、Manoj Kumar、Rajesh Kumar
DOI:10.1016/j.tet.2010.05.042
日期:2010.7
substituted monohydric phenols, containing electron-withdrawing substituents at the ortho position to the phenolic group, with [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser’s reagent) leads to novel tosyloxylation of aromaticring, thereby offering a convenient synthesis of hitherto unknown 4-tosyloxy-2-substituted phenols.