The highly regio- and stereoselective 6-exo-dig mode cyclization of N-acyl-o-alkynylanilines producing 4-alkylidene-3,1-benzoxazines occurred unpredictably by use of a proper catalyst [Pd(OAc)(2)] and an effective additive (acetic acid) under suitable reaction conditions.
Iodine-Catalyzed, Stereo- and Regioselective Synthesis of 4-Arylidine-4H-benzo[d][1,3]oxazines and their Applications for the Synthesis of Quinazoline 3-Oxides
作者:Wen-Chun Lee、Ho-Chuan Shen、Wan-Ping Hu、Wei-Sheng Lo、Chebrolu Murali、Jaya Kishore Vandavasi、Jeh-Jeng Wang
DOI:10.1002/adsc.201200018
日期:2012.8.13
4-Benzylidene-2-aryl-4H-benzo[d][1,3] oxazines have been synthesized with high stereoselectivity and regioselectivities from 2-alkynylbenzamides in the presence of a catalytic amount of I2. In the reaction mechanism, iodine plays a key role in two different aspects as a catalyst, such as to activate the alkyne with the iodinium donor which triggers the cascade, and then as a proper acid source to facilitate
在催化量的I 2存在下,由2-炔基苯甲酰胺以高的立体选择性和区域选择性合成了4-苄基-2-芳基-4 H-苯并[ d ] [1,3]恶嗪。在反应机理中,碘在两个不同方面起着催化剂的关键作用,例如用引发级联反应的碘供体活化炔烃,然后作为适当的酸源以促进催化剂的回收。苯并恶嗪已经被用作直接一步合成喹唑啉3-氧化物衍生物的潜在底物。