- Sc(OTf)3-catalyzed intramolecular diastereoselective cyclization from tert-butoxycarbonyl to acyliminium ion
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An effective approach to access dyadic 1,3-oxazinan-2-ones 8a-8c and 4,4a,5,6-tetrahydro-[1,3]oxazino[3,4-a]quinolin-1(3H)-ones 8d-8h was developed through Sc(OTf)3-catalyzed intramolecular cyclization from tert-butoxycarbonyl to acyliminium io
- Mao, Zhuo-Ya,Wang, Chen,Nie, Xiao-Di,Han, Xiao-Li,Dong, Han-Qing,Si, Chang-Mei,Wei, Bang-Guo
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- Cu(OTf)2catalyzed Ugi-type reaction ofN,O-acetals with isocyanides for the synthesis of pyrrolidinyl and piperidinyl 2-carboxamides
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The Cu(OTf)2catalyzed Ugi-type reactions ofN,O-acetals with isocyanides have been described for the synthesis of pyrrolidinyl and piperidinyl 2-carboxamides. 4-Hydroxy-5-substituted-prolinamides can be obtained in high diastereoselectivities (2
- Mao, Zhuo-Ya,Nie, Xiao-Di,Feng, Yi-Man,Si, Chang-Mei,Wei, Bang-Guo,Lin, Guo-Qiang
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supporting information
p. 9248 - 9251
(2021/09/20)
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- Two-way homologation of aliphatic aldehydes: Both one-carbon shortening and lengthening via the same intermediate
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Aliphatic aldehydes can be homologated to both one-carbon shorter and one-carbon longer homologous carbonyl compounds through the 2–4 steps of reactions via the same intermediates, β,γ-unsaturated α-nitrosulfones, prepared from the proline-catalyzed sequential reactions of several aliphatic aldehydes with phenylsulfonylnitromethane. While the oxidative cleavage of the key intermediates gave one-carbon less homologous carbonyl compounds, the reduction of the same key intermediates followed by an oxidation produced one-carbon more homologous carbonyl compounds.
- Yoo, Jae Won,Seo, Youngran,Park, Jong Beom,Kim, Young Gyu
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- Lithiation-Substitution of N -Boc-2-phenylazepane
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Preparation of 2,2-disubstituted azepanes was accomplished from N - tert -butoxy(N -Boc)-2-phenylazepane by treatment with butyllithium then electrophilic quench. The lithiation was followed by in situ ReactIR spectroscopy and the rate of rotation of the carbamate was determined by variable temperature (VT)-NMR spectroscopy and by DFT studies. Most electrophiles add α to the nitrogen atom but cyanoformates and chloroformates gave ortho -substituted products. Cyclic carbamates were formed from an aldehyde or ketone electrophile. Kinetic resolution with sparteine was only poorly selective. Removal of the Boc group promoted cyclization to a homoindolizidine or an isoindolinone.
- Aeyad, Tahani,Williams, Jason D.,Meijer, Anthony J. H. M.,Coldham, Iain
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supporting information
p. 2765 - 2768
(2017/10/06)
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- Hydrozirconation of four-, five-, six- and seven-membered N-alkoxycarbonyl lactams to lactamols
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A general, practical, and efficient reduction of four-, five-, six- and, seven-membered N-alkoxycarbonyl lactams to the aldehyde oxidation state is reported. The reduction methodology involves the hydrozirconation reaction by Cp2Zr(H)Cl under m
- Piperno, Anna,Carnovale, Caterina,Giofr, Salvatore V.,Iannazzo, Daniela
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supporting information; experimental part
p. 6880 - 6882
(2012/02/05)
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- The versatile conversion of lactams to the α-alkylated azacycles via cyclic N,O-acetal TMS ether
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The efficient preparation of the cyclic N,O-acetals from lactams by DIBAL reduction followed by direct trapping of the resulting N,O-hemiacetals using TMSOTf/pyridine system is described. In addition, the facile nucleophilic addition of various carbon nucleophiles at the carbonyl carbons of the lactams through the corresponding N,O-acetals is also reported.
- Suh, Young-Ger,Kim, Seok-Ho,Jung, Jae-Kyung,Shin, Dong-Yun
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p. 3165 - 3167
(2007/10/03)
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- Efficient and Expeditious Protocols for the Synthesis of Racemic and Enantiomerically Pure Endocyclic Enecarbamates from N-Acyl Lactams and N-Acyl Pyrrolidines
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A mild, practical, and straightforward protocol for the construction of endocyclic enecarbamates starting from N-acyl lactams and N-acyl pyrrolidines is presented. Lactams were reduced to the corresponding α-hydroxycarbamates in good to excellent yields using DIBAL-H, SuperHydride, or NaBH4 followed by β-elimination (dehydration) promoted by trifluoroacetic anhydride in the presence of hindered nitrogenated bases such as 2,6-lutidine, diisopropylethylamine, or triethylamine. Small variations of this protocol permitted the preparation of several endocyclic enecarbamates (12 examples) in good to excellent overall yields (56-96%). The protocol was demonstrated to be applicable to several ring sizes, compatible with different protecting groups, and to be mild enough to prevent racemization of racemization-prone stereocenters. The efficacy of the procedure in the preparation of enantiomerically pure endocyclic enecarbamates was also demonstrated and compared to the commonly used Shono's protocol, which in our hands led to partial racemization of the endocyclic enecarbamate 18c.
- Oliveira, Denilson F.,Miranda, Paulo C. M. L.,Correia, Carlos R. D.
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p. 6646 - 6652
(2007/10/03)
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