Stille coupling approaches to the stereospecific synthesis of 7-[(E)-alkylidene]cephalosporins

Organotin Reagents in Cross‐Coupling Reactions

“…Smith et al [119] used a coupling between a vinyltin and an oxazole triflate as a key step in the 27-step total synthesis of the antiproliferative agent (−)-phorboxazole A. Buynak et al [120] used a number of coupling strategies involving vinyltin and other organotins (aryl and 2-pyridyl), as well as hexamethylditin, in the synthesis of 7-[(E)-alkylidene]cephalosporins, which are potential enzyme inhibitors. Kanekiyo et al [121] used couplings between vinyl-or alkynyltins and organoiodides in the total syntheses of three β-carboline alkaloids.…”

Heteroatomcuprates and α‐Heteroatomalkylcuprates in Organic Synthesis

“…Although the latter reagent gives low yields of acylsilanes, the former one gives higher yields than the lithium silylcuprates (0 to 25 C, 10 h) with highly functionalized acid chlorides [114a]. Stannyl cuprates couple with vinyl halides or triflates [16c-d, 85], and a vinyl stannane produced this way has been used in the synthesis of 7-[(E)-alkylidene]cephalosporins [117]. Alkylation of silylcuprates with alkyl halides and sulfonates has been exploited in a synthesis of silicon-containing alanines for use as non-protenogenic amino acids (Scheme 3.32) [116a].…”

Broad-Spectrum Radical Cyclizations Boosted by Polarity Matching. Carbonylative Access to α-Stannylmethylene Lactams from Azaenynes and CO

“…10 Stille coupling reaction of 2b(Z) with PhI (cat. Pd 2 (dba) 3 , DMF) 11 proceeded to give the stereo-retained phenylation product 5(Z).…”