Rearrangements of 1,6,7-trisubstituted 2-methyl-1,2,3,4-tetrahydroisoquinolinium 2-methylides

Abstract

Reaction of 20 with imino]triphenylphosphorane. To a solution of 20 (0.53 g, 1 mmol) in 25 mL of dry toluene was added [N-(4-methylphenyl)imino]triphenylphosphorane (1.10 g, 3 mmol). The reaction mixture was heated at reflux temperature for 3 h and afterwards at 150 °C in a sealed tube for 12 h. After cooling, the solvent was removed under reduced pressure, and the resulting material was chromatographed (silica gel column; n-hexane/ethyl acetate, 7:3) to give 5e (48%) and 22. 22: yield 51%; mp 243 °C; yellow prisms (ethyl acetate/n-

Competing Rearrangements of Ammonium Ylides: A Quantum Theoretical Study

“…Although there have been a number of complementary experimental studies on the competition between the Sommelet−Hauser and Stevens mechanisms, − these studies employed aromatic rings to provide the participating CC double bond (with a consequent modification in the reaction mechanism), and substituent effects were only investigated as far as substitution on the aromatic ring was concerned . Direct comparisons with our work are difficult; however, it was found in these experiments that electron-deficient aromatic systems favored the Sommelet−Hauser rearrangement, which is consistent with our conclusions about the effect of electron-withdrawing groups. Further theoretical work is required on our part to model these more complex experimental systems.…”

“…In the case of ylides with a β-hydrogen, there is the added possibility of the Hofmann elimination to form an alkene and a less-substituted amine. There has been some experimental investigation into the effect of functional groups and stereochemistry on the ratio of rearrangement products; − however, there has been little theoretical study on the competing pathways.…”

Determining the scope of the lanthanide mediated, sequential hydroamination/C–C cyclization reaction: formation of tricyclic and tetracyclic aromatic nitrogen heterocycles

“…The spectral features matched the reported spectral data. 16 The material was used in the next step without further purification.…”

Ring Expansion of 1,2,3,4-Tetrahydroisoquinolines to Dibenzo[c,f]azonines. An Unexpected [1,4]-Sigmatropic Rearrangement of Nitrile-Stabilized Ammonium Ylides

“…The first approach to this compound class was reported by Zugna and co-workers, who treated 2,2′-bis­bromo­methyl­di­phenyl­methane with sodium cyana­mide or benzyl­amine to give the ring-closed substitution products . Manning and Houlihan patented the synthesis of dibenzo[ c , f ]azonines from iso­indolo[1,2- a ]iso­quino­linum salts by reduction with sodium in liquid ammonia to cleave the central bond between C-12b and nitrogen. , A Sommelet–Hauser rearrangement of 1-phenyl­tetra­hydro­iso­quino­linium methylides to dibenzo[ c , f ]azonines was reported by Sato et al The latest report on this class of hetero­cycles is a patent by Dreux and co-workers describing a sequential reduction, hydrolysis, and intra­molecular cyclo­condensation of ethyl-3-(3-methoxy­benzyl­amino)-4-(3,4-di­methoxy­phenyl)-2-butenoate…”