Palladium Catalysed Tandem Cyclisation–Anion Capture. Part 5: Cascade Hydrostannylation-bis-cyclisation-intramolecular Anion Capture. Synthesis of Bridged- and Spiro-Cyclic Small and Macrocyclic Heterocycles

Organotin Reagents in Cross‐Coupling Reactions

“…Another interesting area is asymmetric allylation of aldehydes, imines, Michael acceptors, or fullerenes, in which allylstannanes are used as an allyl source. A mixture of palladium acetate (0.011 g, 0.05 mmol), triphenylphosphine (0.026 g, 0.1 mmol), and the alkyne (0.5 mmol) in toluene (5 ml) was stirred at 0 • C under nitrogen while tributyltin hydride (0.160 g, 0.5 mmol, 0.148 ml) was added dropwise over 5 min (Scheme 6.18) [76]. The reaction mixture was then allowed to warm to room temperature over 1 h, before being heated at 100 • C for 16 h. After cooling to room temperature, a saturated aqueous solution of potassium fluoride (5 ml) was added and the mixture was stirred for 1 h, filtered, the organic phase was dried (Na 2 SO 4 ), filtered, and the filtrate was concentrated.…”

“…Grigg et al [76] have developed cascade reactions involving palladium-catalyzed hydrostannylation-cyclization-anion capture processes. Thus, starting from O-and N-α,ω-enyne derivatives of 2-iodoaryl ethers and 2-iodoarylamides and Bu 3 SnH, the hydrostannylation (at 25 • C) was followed (at 100-110 • C) by 5-exo-trig cyclization and finally by an intramolecular sp 3 -sp 2 Stille coupling to give a wide range of bicyclic spirocyclic and bridged-ring heterocycles (Scheme 6.18).…”

“…Thus, starting from O-and N-α,ω-enyne derivatives of 2-iodoaryl ethers and 2-iodoarylamides and Bu 3 SnH, the hydrostannylation (at 25 • C) was followed (at 100-110 • C) by 5-exo-trig cyclization and finally by an intramolecular sp 3 -sp 2 Stille coupling to give a wide range of bicyclic spirocyclic and bridged-ring heterocycles (Scheme 6.18). Bn 56% Scheme 6.18 A hydrostannylation-cyclization-anion capture process leading to a spirocyclic skeleton [76].…”

Palladium catalysed tandem cyclisation–anion capture processes. Part 8 : In situ and preformed organostannanes. Carbamyl chlorides and other starter species

“…This strategy has proved extremely powerful in generating complex organotin(IV) anion capture species in situ via regio-selective hydrostannylation of appropriate alkynes as part of a temperature controlled cyclisation-anion capture cascade [20][21][22]. Following the success of the palladium catalysed cyclisation-anion capture with in situ generated vinylstannanes, we decided to investigate anion capture with in situ generated tributylstannyl 1,2-dialkylidenecyclopentanes.…”

Tri-2-furylphosphine

“…hydrogen atoms, otherwise fast β-elimination would ensue. In some cases, both the Heck insertion and the Stille capping are intramolecular 77. In some cases, both the Heck insertion and the Stille capping are intramolecular 77.…”