- Synthesis of homopropargylamines from 2-cyanoazetidines
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2-Cyanoazetidines, easily accessible from β-amino alcohols, undergo ring-cleavage upon reaction with trimethylsilylazide and catalytic amounts of Bu2SnO, to give the corresponding homopropargylamines which are isolated as their N-Boc protected
- Quinodoz,Wright,Drouillat,David,Marrot,Couty
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- Biogenetically inspired total syntheses of lycopodium alkaloids, (+)-flabellidine and (-)-lycodine
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The first asymmetric total synthesis of (+)-flabellidine (2) and the shortest total synthesis of (-)-lycodine (3) were accomplished by a strategy featuring the one-pot construction of a tetracyclic lycodine skeleton from a linear precursor, which was insp
- Azuma, Masayuki,Yoshikawa, Tetsuya,Kogure, Noriyuki,Kitajima, Mariko,Takayama, Hiromitsu
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- Iodocarbamation of N-Homopropargyl Carbamates: Mild and Stereoselective Entry to Functionalized Oxazinan-2-ones
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An efficient and general iodocarbamation of benzyl N-homopropargylcarbamates has been developed by using iodine as the electrophilic agent. This regio- and stereoselective cyclization yielded (E)-6-iodomethyleneoxazinan-2-ones, which can be further transformed through palladium cross-coupling reactions followed by hydrogenation to produce 1,3-oxazinan-2-ones.
- Quinodoz, Pierre,Quelhas, Alexandre,Wright, Karen,Drouillat, Bruno,Marrot, Jér?me,Couty, Fran?ois
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supporting information
p. 2621 - 2626
(2017/05/19)
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- Rhodium-Catalyzed Intramolecular C-H Bond Activation with Triazoles: Preparation of Stereodefined Pyrrolidines and Other Related Cyclic Compounds
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On treatment of triazoles having an N-sulfonyl-protected benzylamine moiety with [Rh2(C7H15CO2)4], intramolecular C-H bond insertion takes place at the benzylic position to give cis-N-sulfonyl-2-aryl-3-[(sulfonylimino)methyl]pyrrolidines in good yields and with highly stereoselectivities. Analogously, the similar treatment of triazoles having an ether or even an alkyl moiety affords 2-alkyl- or 2-aryl-3-[(sulfonylimino)methyl]tetrahydrofurans or a 2-alkyl-3-[(sulfonylimino)methyl]cyclopentane in good yields. Three is a magic number: On treatment of triazoles with [Rh2(C7H15CO2)4], the rhodium catalyst plays three roles, denitrogenation, C-H bond activation, and stereoselective cyclization, providing a new method for heterocycle synthesis. Intramolecular C-H bond insertion takes place at the benzylic position to give pyrrolidines and related heterocycles in good yields.
- Senoo, Masato,Furukawa, Ayana,Hata, Takeshi,Urabe, Hirokazu
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supporting information
p. 890 - 895
(2016/01/16)
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- Regioselective Amine–Borane Cyclization: Towards the Synthesis of 1,2-BN-3-Cyclohexene by Copper-Assisted Triazole/Gold Catalysis
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The combination of triazole/gold (TA-Au) and Cu(OTf)2is identified as the optimal catalytic system for promoting intramolecular hydroboration for the synthesis of a six-membered cyclic amine–borane. Excellent yields (up to 95 %) and regioselectivities (5-exo vs. 6-endo) were achieved through catalyst control and sequential dilution. Good functional-group tolerance was attained, thus allowing the preparation of highly functionalized cyclic amine–borane substrates, which could not be achieved using other methods. Deuterium-labeling studies support the involvement of a hydride addition to a gold-activated alkyne with subsequent C?B bond formation.
- Motika, Stephen E.,Wang, Qiaoyi,Akhmedov, Novruz G.,Wojtas, Lukasz,Shi, Xiaodong
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supporting information
p. 11582 - 11586
(2016/10/24)
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- Enantio- and diastereoselective palladium catalysed arylative and vinylative allene carbocyclisation cascades
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The enantioselective synthesis of heavily decorated spirolactams has been accomplished via an arylative or vinylative allene carbocyclisation cascade. Mediated by silver phosphate, a range of allene-linked pro-nucleophiles and aryl or vinyl iodides were reacted in the presence of catalytic Pd(OAc)2 and chiral bis(oxazoline) ligands to afford the spirolactam products in good yields and high enantio- and diastereoselectivities. The Royal Society of Chemistry 2013.
- Li, Meiling,Hawkins, Alison,Barber, David M.,Bultinck, Patrick,Herrebout, Wouter,Dixon, Darren J.
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supporting information
p. 5265 - 5267
(2013/06/27)
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- Synthesis of α-CN and α-CF3 N-heterocycles through tandem nucleophilic additions
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Using a readily available secondary aminoalkyne as starting material, a powerful strategy was discovered to prepare precursors of biologically important unnatural cyclic aminoacids and fluorinated N-heterocycles with important ring sizes (e.g., 5-7) in a
- Han, Junbin,Xu, Bo,Hammond, Gerald B.
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supporting information; experimental part
p. 3450 - 3453
(2011/08/07)
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- Palladium-catalysed cyclisation of N-alkynyl aminomalonates
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Go around in (hetero)cycles! The palladium-catalysed tandem cyclisation/coupling reaction of alkynyl- and alkenyl-substituted aminomalonates leads to highly functionalised pyrrolidines and piperidines in good yield (see scheme). The reaction allows efficient access to a broad range of synthetically valuable building blocks.
- Hess, Wilfried,Burton, Jonathan W.
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supporting information; experimental part
p. 12303 - 12306
(2011/02/23)
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- Gold-catalyzed synthesis of alkylidene 2-oxazolidinones and 1,3-oxazin-2-ones
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N-Boc-protected alkynylamines are converted into the corresponding alkylidene 2-oxazolidinones or 2-oxazinones under very mild reaction conditions in the presence of 1-5 mol % of a cationic Au(I) complex. The scope of the reaction is very general, providi
- Robles-Machin, Rocio,Adrio, Javier,Carretero, Juan Carlos
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p. 5023 - 5026
(2007/10/03)
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- Carbene reactions of α-oxacyclo- and α-azacyclo-N-aziridinylimines: Effect of heteroatom and ring size in the ring expansion reaction
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Carbenes, generated from thermolysis of α-oxacyclo- and α-azacyclo-N-aziridinylimines in refluxing toluene, underwent ring expansions via insertion of alkyl carbenes into carbon-carbon bonds and intramolecular ammonium ylide formations, respectively. Ring expansion reaction of α-oxetanyl-N-aziridinylimines occurred via alkylidenecarbene intermediates, whereas thermal reaction of α-azetidinyl-N-aziridinylimines afforded α-aminoacetylene compounds via 1,2-H migration of alkylidenecarbene intermediates.
- Kim,Yoon
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p. 1622 - 1630
(2007/10/03)
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- Aldehyde Addition and Copper-Mediated Allylation of Bicyclic Alkoxytitanacyclopentenes and -Pentadienes: New Selectivities and an Unusual Reaction
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Bicyclic titanacyclopentenes generated in situ from 1,6-enynes and (η2-propene)Ti(O-i-Pr)2 (1) reacted with aldehydes at their alkenyl-titanium bond in the absence or presence of Ti(O-i-Pr)nCl4-n (n = 2 or 3) to give allyl alcohols such as 5-7 as a nearly single stereoisomer in good yields. Upon workup with DCl/D2O or iodine, deuterio and iodo derivatives, 8 and 9, were obtained. Bicyclic titanacyclopentadienes prepared analogously from 1,6- or 1,7-diynes and 1 also reacted with aldehydes in the presence of an additional equivalent of Ti(O-i-Pr)2Cl2 to afford 1,2-dialkylidenecyclopentanes or -cyclohexanes having an alcohol moiety in their side chain in good yields. In place of the simple hydrolysis, deuteriolysis or iodinolysis gave the corresponding derivatives such as 21 or 22. Treatment of 1,6-enyne 10 with 1 in the standard way and then with a slight excess of i-PrMgCl at -50°C generated a new titanium species that, upon reaction with aldehydes, afforded unexpected adducts 34 and 41-45 virtually as a single isomer. Copper-mediated allylation of dialkoxytitanacyclopentene such as 3 with allyl bromide proceeded at their vinyl-titanium bond to give 48 and 50. Likewise, dialkoxytitanacyclopentadiene prepared from 29 and 1 underwent the regioselective copper-mediated monoallylation to give a 9:1 mixture of 53 and 54. Upon workup with deuteriochloric acid, the corresponding deuterated product was obtained with a high degree of deuterium incorporation.
- Urabe, Hirokazu,Sato, Fumie
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p. 1245 - 1255
(2007/10/03)
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- The first selective antagonist for a GABAC receptor
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(1,2,5,6-Tetrahydropyridine-4-yl)methylphosphinic acid (TPMPA, 1), which is synthesized in six steps from 3-butyn-1-ol, is the first γ-aminobutyric acid (GABA) receptor antagonist that shows strong selectivity for mammalian GABAc receptors. Copyright
- Murata, Yoshinori,Woodward, Richard M.,Miledi, Ricardo,Overman, Larry E.
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p. 2073 - 2076
(2007/10/03)
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- Heterocycles in Asymmetric Synthesis. Part 1. Construction of the Chiral Building Blocks for Enantioselective Alkaloid Synthesis via an Asymmetric Intramolecular Michael Reaction
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The asymmetric intramolecular Michael reaction of acyclic compounds ethyl (E)-4-but-2-enoate 9, and ethyl (E)-5-pent-2-enoate 10 was investigated under a variety of conditions, and the pyrrolidine ethyl (4-acetyl-1-benzylpyrrolidin-3-yl)acetate 11 and piperidine ethyl (3-acetyl-1-benzylpiperidin-4-yl)acetate 12, versatile chiral building blocks for alkaloid synthesis, were obtained in moderate to excellent optical yield.Cyclization of the aforementioned but- and pent-2-enoate using (R)-1-phenylethylamine in THF in the presence of molecular sieves 5 Angstroem gave the (+)-pyrrolidine derivative (+)-11 and the (-)-piperidine derivative (-)-12 in 60 and 90percent ee, respectively.When (S)-1-phenylethylamine was used, pyrrolidine (-)-11 and piperidine derivatives (+)-12 were obtained in similar optical yields, respectively.The ee of (-)- and (+)-piperidine derivatives increased up to 98percent upon recrystallization of their hydrobromid salts.
- Hirai, Yoshiro,Terada, Takashi,Yamazaki, Takao,Momose, Takefumi
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p. 509 - 516
(2007/10/02)
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