attacked by arene nucleophiles with high facial diastereoselectivity (dr >/= 94/6). Benzylic cations, such as 2, were generated under acidic conditions and reacted with arenes in intra- and intermolecular Friedel-Crafts alkylation reaction. The depicted reaction 1 --> 3 represents one example for the unprecedented, highly diastereoselectiveintermolecular Friedel-Crafts alkylation reactions which were
Novel chiral (salen)Mn(<scp>iii</scp>) complexes containing a calix[4]arene unit in 1,3-alternate conformation as catalysts for enantioselective epoxidation reactions of (Z)-aryl alkenes
作者:Carmela Bonaccorso、Giovanna Brancatelli、Francesco P. Ballistreri、Silvano Geremia、Andrea Pappalardo、Gaetano A. Tomaselli、Rosa M. Toscano、Domenico Sciotto
DOI:10.1039/c3dt52550c
日期:——
Two new chiral calix[4]arene-salen ligands 1a,b, based on calix[4]arene platforms in 1,3-alternate conformation, have been prepared by a new general syntheticpathway. Their Mn(III) complexes, 3a,b, have shown fairly good efficiency in the asymmetric epoxidation of styrene and substituted styrenes, whereas excellent catalytic activity and selectivity were observed with rigid bicyclic alkenes, namely
Stereospecific Deoxygenation of Aliphatic Epoxides to Alkenes under Rhenium Catalysis
作者:Takuya Nakagiri、Masahito Murai、Kazuhiko Takai
DOI:10.1021/acs.orglett.5b01583
日期:2015.7.2
is effective for the deoxygenation of unactivated aliphatic epoxides to alkenes. The reaction proceeds stereospecifically with variously substituted epoxides under neutral conditions and is compatible with various functional groups. Protection and deprotection of a double bond functionality using an epoxide are shown as an example of the current rhenium-catalyzed deoxygenation protocol. The effect
催化量的Re 2 O 7和亚磷酸三苯酯作为还原剂的组合对于未活化的脂族环氧化物脱氧为烯烃是有效的。该反应在中性条件下与各种取代的环氧化物立体定向进行,并且与各种官能团相容。作为当前rh催化的脱氧方案的实例,显示了使用环氧化物对双键官能团的保护和脱保护。还研究了还原剂对立体选择性的影响,表明使用缺电子的膦或亚磷酸酯是立体特异性脱氧的关键。