67902-35-6Relevant academic research and scientific papers
Platinum-catalyzed, one-pot tandem synthesis of indoles and isoquinolines via sequential rearrangement of amides and aminocyclization
Okamoto, Noriko,Takeda, Kei,Yanada, Reiko
experimental part, p. 7615 - 7625 (2011/02/25)
By using platinum(II) chloride as a Lewis acid catalyst, concise and efficient syntheses of indole carbamates, 1,2-dihydroisoquinoline carbamates, macrocyclic indole carbamates, indole ureas, and indole phosphoranes have been achieved via tandem Hofmann-t
Efficient regio- And stereoselective formation of azocan-2-ones via 8-endo cyclization of α-carbamoyl radicals
Fang, Xinqiang,Liu, Kun,Li, Chaozhong
supporting information; experimental part, p. 2274 - 2283 (2010/05/01)
The iodine-atom-transfer 8-endo cyclization of α-carbamoyl radicals was investigated experimentally and theoretically. With the aid of Mg(CIO 4)2 and a bis(oxazoline) ligand, N- ethoxycarbonylsubstituted N-(pent-4-enyl)-2-iodoalkanamides underwent 8-endo cyclization leading to the formation of only the corresponding 3,5-trans-substituted azocan-2-ones in excellent yields. Similarly, the BF 3·OEt2/H2O-promoted reactions of N-ethoxycarbonyl-N-(2-allylaryl)-2-iodoalkanamides afforded exclusively the benzazocanone products with a 3,5-cis configuration in high yields. The bidentate chelation of substrate radicals not only significantly improved the efficiency of cyclization but also resulted in the change of stereochemistry of azocanone products from 3,8-iransto 3,8-cis. Theoretical calculations at the UB3LYP/6-31G* level revealed that the cyclization of N-carbonyl- substituted α-carbamoyl radicals occurs via the E-conformational transition states without the presence of a Lewis acid. On the other hand, the cyclization proceeds via the Z-conformational transition states when the substrates form the bidentate chelation with a Lewis acid. In both cases, the 8-endo cyclization is always fundamentally preferred over the corresponding 7-exo cyclization. The complexed radicals having the more rigid conformations also allow the better stereochemical control in the iodine-atom-abstraction step. To further understand the reactivity of a-carbamoyl radicals, the competition between the 8-endo and 5-exo cyclization was also studied. The results demonstrated that the 8-endo cyclization is of comparable rate to the corresponding 5-exo cyclization for a-carbamoyl radicals with fixed Z-conformational transition states. As a comparison, the 8-endo mode is fundamentally preferred over the 5-exo mode in the cyclization of NH-amide substrates because the latter requires the Z-conformational transition states, whereas the former proceeds via the more stable E-conformational transition states.
Cyclofunctionalization of Olefinic Urethanes Using Benzeneselenenyl Chloride in the Presence of Silica Gel: A General Route to Nitrogen Heterocycles
Clive, D. L. J.,Farina, Vittorio,Singh, Alok,Wong, Chi Kwong,Kiel, William, A.,Menchen, Steven M.
, p. 2120 - 2126 (2007/10/02)
Ethyl urethanes derived from Δ4 or Δ5 olefinic amines undergo cyclofunctionalization to afford pyrrolidines and piperidines, respectively, when treated with benzeneselenenyl chloride.The reaction is an efficient one when carried out in the presence of silica gel, yields generally being above 80percent for the examples studied.
