“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In 1989, Beak disclosed that unsubstituted Boc-protected azaheterocycles may be effectively functionalized at the a-position through a lithiation/alkylation sequence. 19 Several researchers, [20][21][22][23][24][25][26] including one of us, 27,16 have since extended the Beak methodology to include sequential a-functionalizations en route to access a,a-and a,a 0 -disubstituted N-heterocycles, in both racemic and enantioenriched forms. It has been shown that the lithiation of phenyl pyrrolidine S-1 (Fig.…”