Diastereoselective synthesis of α,α,α′-trisubstituted pyrrolidines and piperidines by directed sequential lithiation/alkylation

Trapping of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles: Controlling the formation of α-amino quaternary and vicinal stereocenters

“…2A) proceeds satisfactorily to afford the corresponding trisubstituted products (i.e., 2), in good to excellent diastereoselectivities. 32 Additionally, we and Sarpong have revealed that the addition of organolithium nucleophiles to the β-position of α-arylated piperidine enecarbamates such as 3 followed by protonation of the resulting intermediate tertiary organolithium, is possible, under additive-free conditions (see 4, Fig. 2B).…”

“…Accordingly, our interest in these functionalized azaheterocycles 11,[24][25][26][27][28][29][30][31] has recently led us to the discovery that α′-lithiation/trapping of α-alkyl-α-aryl disubstituted piperidines such as 1 ( Fig. 32 Additionally, we and Sarpong have revealed that the addition of organolithium nucleophiles to the β-position of α-arylated piperidine enecarbamates such as 3 followed by protonation of the resulting intermediate tertiary organolithium, is possible, under additive-free conditions (see 4, Fig. 32 Additionally, we and Sarpong have revealed that the addition of organolithium nucleophiles to the β-position of α-arylated piperidine enecarbamates such as 3 followed by protonation of the resulting intermediate tertiary organolithium, is possible, under additive-free conditions (see 4, Fig.…”

Regiocontrolled synthesis of (hetero)aryl and alkenyl dehydropyrrolidines, dehydropiperidines and azepenes by Ru-catalyzed, heteroatom-directed α-C–H activation/cross-coupling of cyclic enamides with boronic acids

“…30 Continuing our quest for expedient-, practical-and complementary-methods for accessing functionalized Department of Chemistry, Central Washington University, Ellensburg, WA 98926, USA. E-mail: TimothyB@cwu.edu azaheterocycles, 24,25,[33][34][35][36][37][38][39][40][41][42][43] and the cognizant of the inherently high reactivity of unfunctionalized cyclic enamides such as V (relative to the corresponding saturated cyclic amine), it was surmised that regioselective sp 2 α-C-H functionalization/crosscoupling of the latter with boronic acids, under ruthenium catalysis, offered an attractive approach (Fig. 2E).…”