Front Cover Picture: Lewis Acid‐Catalyzed Formal (4+2)‐ and (2+2+2)‐Cycloaddition Between 1‐Azadienes and Styrylmalonates as Analogues of Donor‐Acceptor Cyclopropanes (Adv. Synth. Catal. 23/2021)

Abstract

The front cover picture, designed by Pavel G. Sergeev and Daria I. Filina, illustrates the comparison between reactivities of donor-acceptor cyclopropanes and styrylmalonates in the Lewis acid-catalyzed formal cycloadditions with conformationally non-rigid azadienes. On transition from one synthetic analogue to another, the regioselectivity of the addition can change dramatically from the (3+2)- to the (4+2)-pathway. The choice of styrylmalonates has been shown to be preferred in these reactions. The (4+2)-cycloaddition between styrylmalonates and azadienes was optimized to provide access to the diastereoselective synthesis of substituted tetrahydropyridines in high yields. Details can be found in the Research Article by P. G. Sergeev, R. A. Novikov and Y. V. Tomilov (P. G. Sergeev, R. A. Novikov, Y. V. Tomilov, Adv. Synth. Catal. 2021, 363, 5293–5300; DOI: 10.1002/adsc.202100453).