Tetrahedron Letters,Vo1.30,No.25,pp 3259-3262,1989 on40-4039/89 $3.00 + -00 Printed in Great Britain Maxwell Pergamon Macmillan plc THE UNCATALYZED DIELS-ALDER REACTION OF MINES WITH BIS(PHENYLSULFONYL)SUBSTlTUTED DIENES Albert Padwa*, Brian Harrison and Bryan H. Norman Department of Chemistry Emory University, Atlanta, Ga. 30322 Abstract: The reaction of 2,3-bis(phenysulfonyi)- 1,3-butadiene with arylimines affords N-alkyl-3,5- bis(phenylsulfonyl)- 1,2,5,64etrahydropyridines in high yield. Multifunctional 1,3-dienes often exhibit high regio and stereospecificity toward dienophiles and consequently these dienes are becoming well established as useful intermediates in organic synthe- sis.le5 Certain derivatives of imines have been employed in cycloaddition chemistry with several heterosubstituted dienes, opening new opportunities for the construction of aza heterocyclic com- pounds.6 Typically, imino Diels-Alder additions are successful only if the imine is activated 7~8 in intra- molecular additions9 or involves the use of an iminium salt. lo Our interest in this area is concerned with the uncatalyzed Diels-Alder cycloaddition of 2,3-bis(phenylsulfonyl)-I ,3-butadiene (I)” with various C-N pi-bonds. In an earlier report, we described our initial studies which focused on the reaction of 1 with oximes to give azaoxabicyclic adducts. ‘* We have now studied the reaction of 1 with a variety of imines and find that a rather novel reaction occurs in excellent yield to give a rear- ranged Diels-Alder cycloadduct. This communication documents the results of these studies. As our first model we investigated the Diels-Alder reaction of la with N- benzylidenemethylam- ine. A typical reaction was carried out by simply stirring the two reagents in Tethylene chloride at 25OC for 24 h. The structure of the resulting cycloadduct 2a (90%) was assigned on the basis of its characteristic spectral data and was further established by an X-ray single crystal structure analysis. This surprising result suggested a further study of la with other imines so as to establish the general- ity of the process. Indeed compound la participates as the diene component with several imines Ar*‘SO CH &I 1 At’CH =NR - 25 oc SO *AT SO PAr la; Af=Ph 1 b; Ar=(o-NO,)C,H, 2a; Ar=Ar*=Ph; R&H, b; Ar=(o-NO&H,; ArkPh; R=CHB c; Ar=Ar*=Ph; R&H2Ph d; Ar=(o-NO&-H,; A&Ph; R=CH2Ph e; Ar=Ph; A&a-Naphth; R=CHPPh f; Ar*‘=(o-NO,)C,H,;Ar=Ar*=Ph;R=CH, 3259