- Observations concerning the synthesis of heteroatom-containing 9-membered benzo-fused rings by ring-closing metathesis
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A set of benzo-fused dienes with a 1,9-relationship and containing a variety of nitrogen and oxygen heteroatoms was readily synthesized. These dienes were then treated with the Grubbs second generation catalyst with the aim of synthesizing the 9-membered benzannelated heterocycles containing two heteroatoms (either O,O, NR,NR or O,NR where R = Ts or Boc). As previously observed in the literature, many of the dienes did not give the expected ring-closed product. However, a number of the desired products did form, namely with the 1,2-dihydrobenzo[c][1,5]oxazonin-7(5H)-one, 5,7-dihydrobenzo[b][1,5]oxazonine-6(2H)-carboxylate and 2,5,6,7-tetrahydrobenzo[b][1,5]oxazonine cores, albeit in poor yields. Rather surprisingly, the N-allyl-N-(2-(N-allyl-4-methylphenylsulfonamido)benzyl)-4-methylbenzenesulfonamide scaffold gave the desired ring-closed 1,6-ditosyl-2,5,6,7-tetrahydro-1H-benzo[b][1,5]diazonine in a high yield. Furthermore, when treated with the catalyst [RuClH(CO)(PPh3)3] the alkene isomerized into conjugation only with the benzylic NTs group and not with the phenyl NTs group to afford the 1,6-ditosyl-2,3,6,7-tetrahydro-1H-benzo[b][1,5]diazonine structure.
- Aderibigbe, Blessing A.,Green, Ivan R.,Mabank, Tanya,Janse van Rensburg, Mari,Morgans, Garreth L.,Fernandes, Manuel A.,Michael, Joseph P.,van Otterlo, Willem A.L.
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p. 4671 - 4683
(2017/07/10)
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- A novel strategy for the synthesis of medium-sized lactams
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(Matrix presented) A novel method for the synthesis of medium-sized lactams based on an auxiliary-mediated combined tethered/templated strategy is presented. Cyclization by a tethered ring-closing metathesis reaction was followed by a templated transannular aminolysis reaction to give seven-to ten-membered lactams in good yields.
- Bieraeugel, Hans,Jansen, T. Paul,Schoemaker, Hans E.,Hiemstra, Henk,Van Maarseveen, Jan H.
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p. 2673 - 2674
(2007/10/03)
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- Synthesis of novel α-substituted and α,α-disubstituted amino acids by rearrangement of ammonium ylides generated from metal carbenoids
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(equation presented) A new and general four-step synthesis of protected a-substituted and α,α-disubstituted amino acids has been developed. The key step involves intramolecular ammonium ylide generation from a copper carbenoid with concomitant [2,3] rearr
- Clark, J. Stephen,Middleton, Mark D.
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p. 765 - 768
(2007/10/03)
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- The stereochemistry of organometallic compounds. XLIII* rhodium-catalysed reactions of 2-(alkenyloxy)benzylamines and 2-(N-allyl-N-benzylamino)benzylamine
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Reactions of 2-(allyloxy)benzylamines with H2/CO in the presence of rhodium catalysts give 1,3-benzoxazines, and 2-(N-allyl-N-benzylamino)benzylamine gives a quinazoline. These reactions have been shown to involve allylic cleavage followed by regioselective carbonylation at the internal carbon atom as demonstrated by crossover experiments. Reactions of longer chain (alkenyloxy)benzylamines under similar conditions give polymeric material.
- Campi, Eva M.,Jackson, W. Roy,McCubbin, Quentin J.,Trnacek, Andrew E.
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p. 219 - 230
(2007/10/03)
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