Synthesis of Amino Acid derived 2-Methylene Morpholines and 3,4-dihydro-2H-1,4-Oxazines via Ag (I) promoted Intra-molecular Cyclization of Alkynols

Protecting group dependent change in product formation in Ag (I) promoted intra-molecular cyclization is revealed on amino acid derived alkynols. We herein report that the N-Boc protected amino acid derived alkynols provide kinetically controlled 2-methylene morpholines while N-Tosyl protected amino acid derived alkynols afford thermodynamically controlled 3,4-dihydro-2H-1,4-oxazines via Ag (I) promoted intra-molecular cyclization.