- Overcoming the Deallylation Problem: Palladium(II)-Catalyzed Chemo-, Regio-, and Stereoselective Allylic Oxidation of Aryl Allyl Ether, Amine, and Amino Acids
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We report herein a Pd(II)/bis-sulfoxide-catalyzed intramolecular allylic C-H acetoxylation of aryl allyl ether, amine, and amino acids with the retention of a labile allyl moiety. Mechanistically, the reaction proceeds through a distinct double-bond isomerization from the allylic to the vinylic position followed by intramolecular carboxypalladation and the β-hydride elimination pathway. For the first time, C-H oxidation of N-allyl-protected amino acids to furnish five-membered heterocycles through 1,3-syn-addition is established with excellent diastereoselectivity.
- Begam, Hasina Mamataj,Jana, Ranjan,Manna, Kartic,Samanta, Krishanu
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supporting information
p. 7443 - 7449
(2020/10/09)
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- 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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- Benzoylureas as removable cis amide inducers: Synthesis of cyclic amides via ring closing metathesis (RCM)
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Rapid and high yielding synthesis of medium ring lactams was made possible through the use of a benzoylurea auxiliary that serves to stabilize a cisoid amide conformation, facilitating cyclization. The auxiliary is released after activation under the mild conditions required to deprotect a primary amine, such as acidolysis of a Boc group in the examples given here. This methodology is a promising tool for the synthesis of medium ring lactams, macrocyclic natural products and peptides.
- Brady, Ryan M.,Khakham, Yelena,Lessene, Guillaume,Baell, Jonathan B.
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supporting information; experimental part
p. 656 - 658
(2011/03/22)
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- Concise strategy for the synthesis of elevenmembered and ansa-bridged thirteen-membered lactone macrolides by ring-closing metathesis reaction
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The eleven-membered macrolides and thirteen-membered ansa-bridged macrolides have been synthesized successfully ring-closing metathesis reaction in the absence of the additive Ti(OiPr)4, which is essential for the metathesis of the ester precursors.
- Majumdar, Krishna C.,Chattopadhyay, Buddhadeb,Ansary, Inul
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experimental part
p. 472 - 477
(2009/10/17)
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- ALLYLQXY AND ALKYLOXY BENZOIC ACID DELIVERY AGENTS
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The present invention relates to pharmaceutical compounds for delivering active agents, such as biologically or chemically active agents, to a target. The invention also relates to pharmaceutical compositions comprising at least one delivery agent compound of the present invention and at least one active agent, and unit dosage forms comprising such compositions. Methods for the preparation and administration of the pharmaceutical compositions are also disclosed.
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Page/Page column 31
(2008/12/07)
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- Pyrolysis of O-Allyl Salicylic Amides and Esters, and Related Compounds: Foemation of Isoindolones and Phthalides
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Flash vacuum pyrolysis of O-allyl salicylic alkylamides and alkyl esters gives isoindolones and phthalides, respectively, in low (20-40percent) yield.The mechanism involves generation of the phenoxyl radical, regiospecific hydrogen-atom transfer from the alkylamide (or alkyl ester) group and cyclization.A similar sequence was observed with thiophenoxyl radicals.
- Black, Michael,Cadogan, J. I. G.,McNab, Hamish
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p. 155 - 160
(2007/10/02)
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