Tandem Cyclization of Alkynylmetals Bearing a Remote Leaving Group via Cycloalkylidene Carbenes

Abstract

Treatment of terminal alkynes bearing a remote leaving group with MNR(2) (M = Li, Na, K) gives bicyclo[n.3.0]-1-alkenes (n = 3, 4). The tandem cyclization proceeds through a mechanism involving exo-cyclization of an alkynylmetal intermediate and intramolecular C-H insertion of the resulting carbenoid.

Alkylative Carbocyclization of ω‐Iodoalkynyl Tosylates with Alkynyllithium Compounds Through a Carbenoid‐Chain Process Leading to (1‐Iodoprop‐2‐ynylidene)tetrahydrofurans and ‐cyclopropanes

“…Crystal data: C 22 H 21 OI; M = 428.31; monoclinic; space group P2 1 /a (no. 14); a = 17.523(8), b = 7.512(2), c = 14.123(4) ; b = 96.42(3)8; V = 1847.5 (10) 3 ; Z = 4; 1 calcd = 1.540 g cm À3 ; FA C H T U N G T R E N N U N G (000) = 856; reflections collected/unique 4445/3267 (R int = 0.134). The structure was solved by direct methods (SHELXL-97) and refined by www.chemeurj.org full-matrix least-squares methods on F 2 with 188 parameters.…”

“…The carbocyclization reactions are proposed to proceed through a new carbenoid-chain process involving the exo cyclization of a lithium aceis deprotonated by LDA to give lithium acetylide 7 (initiation step). In the chain cycle, acetylide 7 undergoes facile exo cyclization at the b position of the acetylide moiety to generate I,Li-alkylidenecarbenoid 8, [10] which is protonated by 5 a to give product 6 a, with simultaneous regeneration of acetylide 7. The type 2 carbenoid-chain process is also responsible for the cycloisomerization of diiodoalkyne 5 b (Y = I, Z = O, CH 2 , n = 1,2) to give diiodomethylene derivatives 6 b (Y = I, Z = O, CH 2 , n = 1,2).…”

Recent Advances in Metal Nanoparticles Stabilization into Nanopores of Montmorillonite and Their Catalytic Applications for Fine Chemicals Synthesis

“…Earlier, propargylamines were prepared by addition of metallated alkynes to an imine. However, these metal alkynylides are relatively difficult to handle and require strictly controlled conditions, otherwise, they form large amounts of waste materials (313). In recent years, various mid-and late transition metal catalysts supported on different matrixes have been used for A 3 coupling reactions (314).…”

Unprecedented one-pot multicomponent synthesis of propargylamines using Amberlyst A-21 supported CuI under solvent-free conditions

“…[1][2][3][4][5][6][7] Indeed, a number of drugs contain the propargylamine backbone and are mostly targeted at treating neurodegenerative disorders, including the renowned anti-Parkinsonian Rasagiline. [10][11][12][13] However, these methods not only require strict control of reaction conditions and stoichiometry but also occasionally pose challenges in obtaining or handling the required starting materials. [10][11][12][13] However, these methods not only require strict control of reaction conditions and stoichiometry but also occasionally pose challenges in obtaining or handling the required starting materials.…”