Reactions Of N-tosyl Amino Group As A Leaving Group And Synthesis Of1,4-Heterocycles In The Presence Of RE（OTF）₃

Chemists have maintained a great enthusiasm on RE(OTf)3catalyzed reactions. RE(OTf)3is one of the most common class of rare earth salts, with the advantage of great Lewis acidity even in pure water, and reusability without significant loss of activity. RE(OTf)3promoted a variety of multicomponent reactions and domino processes for the synthesis of some complex motifs. RE(OTf)3can also perform great effects on inactive substrates in conjuction with other Lewis acids, Br(?)nsted acids, et al.. In asymmetric chemistry, cooperated with several ligands, rare earth salts catalyzed reactions with good diastereoselectivities and enantioselectivities. In continuation of our studies on the use of lanthanide salts, we insisted on the introduction of new methodologies of RE(OTf)3as catalysts.The benzylation and alkylation of various1,3-dicarbonyl compounds with sulfonamides in the presence of Yb(OTf)3was investigated. N-Tosyl amino group was proved to be a stable and green leaving group, this property gave rise to a cleavage of sp3C-N bonds in the cross-coupling reactions. Reports on the cleavage of C-N bonds were rare for two reasons, one was the hardship of the leaving property of amino group, the other one was that people were more interested in the preparation of intermediates containing amino group in the past. Recently the number of new compounds with biological activity was expanded rapidly, so that methodologies of the conversion of amino group to other functional groups were more and more urgent. Our work would be a good supplement for this area, the advantages of the reactions were high yields(up to100%), broad scope, mild conditions, use of cheap catalysts and simplicity of operation with TSNH2as the only side product. Meanwhile, we tried1,2-aryl shift reaction with tosyl-amino group as a leaving group.N-(furan-2-ylmethylene)-4-methylbenzenesulfonamide was used as substitute of2-furaldehyde to work with secondary amines under catalyst-free conditions in moderate yields(up to65%). Furthermore, TsNH2was reported as the catalyst with its excellent leaving property for the first time to construct the4,5-diaminocyclopent-2-enones. The products were separated as trans-diastereomers with good yields(up to65%). The reactions were free of metal, green and convenient. Leaving of the N-Tosyl amino group was the key step for the conversion and the intermediate was detected by LC-MS analysis. More importantly, the work gave us a clue that TsNH2could perform as a promoter for the reactions.We also have a deep research on the synthesis of1,4-heterocycles catalyzed by La(OTf)3An economical, novel, and practical protocol for the form of new cis-1,4-benzoxazine moiety via domino Piancatelli/C-N coupling/Michael addition process with5mol%La(OTf)3as catalyst was developed. The yield was up to92%. Then we tried to construct other1,4-heterocycles employing this scheme, fortunately, we obtained a batch of new1,2,3,4-tetrahydroquinoxaline derivatives. This method should be valuable for the construction of kinds of compounds with biological and medicinal activities. Amino acids derived ligands were designed and we tried to make use of them to complex with RE(OTf)3for the purpose of asymmetric catalysis. Some1,5-hydrogen migration reactions were also explored.