The chemoselective alkynylation of N-sulfonylamides versus amides and carbamates using TMS-EBX as an alkynylating agent leads to the formation of non-symmetrical tetrahydropyrazines from orthogonally protected diamines.

The diastereoselective synthesis of various substituted morpholines has been achieved from vinyloxiranes and amino-alcohols under sequential Pd(0)-catalyzed Tsuji−Trost/Fe(III)-catalyzed heterocyclization. Using the same strategy, 2,6-, 2,5-, and 2,3-disubstituted as well as 2,5,6-and 2,3,5-trisubstituted morpholines were obtained in good to excellent yields and diastereoselectivities.