- N-(tert-Butoxycarbonyl)-2-(tert-butyldimethylsiloxy)pyrrole: A Promising Compound for Synthesis of Chiral Nonracemic Hydroxylated Pyrrolidine Derivatives
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N-t-Boc-2-(tert-butyldimethylsiloxy)pyrrole has been synthesized from pyrrole and used to prepare enantiomerically pure pyrrolinones 5, 6, 15, and 16 and polyhydroxylated pyrrolidinones of type 11 and 12.
- Casiraghi, Giovanni,Rassu, Gloria,Spanu, Pietro,Pinna, Luigi
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- Uncatalyzed, diastereoselective vinylogous Mukaiyama aldol reactions on aqueous media: Pyrrole vs furan 2-silyloxy dienes
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The first uncatalyzed, diastereoselective vinylogous Mukaiyama aldol reaction is reported, between pyrrole/furan-based dienoxy silanes and aromatic aldehydes on salty water/methanol medium, at almost human body temperature, under ultrasonic irradiation. W
- Curti, Claudio,Battistini, Lucia,Zanardi, Franca,Rassu, Gloria,Zambrano, Vincenzo,Pinna, Luigi,Casiraghi, Giovanni
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- Short synthesis of pulchellalactam
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tert -Butyl 4-methyl-2-oxo-2,5-dihydro-1 H -pyrrole-1-carboxylate 4 was synthesized by a short two-step procedure: regioselective 1,3-dipolar diazomethane cycloaddition to N -Boc-pyrrolinone 2 and thermolysis of the adduct. The compound 4 could be converted in one step into pulchellalactam. Copyright Taylor & Francis Group, LLC.
- Hermet, Jean-Paul,Caubert, Virginie,Langlois, Nicole
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- Lewis acid-catalyzed michael addition reactions of N-Boc-2-silyloxypyrroles to 3-acryloyl-2-oxazolidinone
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Among several Lewis acids examined, Sc(OTf)3 (10 mol%) was found to be the most effective catalyst to promote a Michael addition reaction of N-Boc-2-(tert-butyldimethylsilyloxy)pyrrole to 3-acryloyl-2-oxazolidinone. A slow addition of the 2-silyloxypyrrole in the presence of 1,1,1,3,3,3-hexafluoro-2-propanol (5 equiv.) at -25 °C were needed to obtain good yield (77 - 80%). The asymmetric version of the reaction could be performed with good enantioselectivity (up to 82% ee) by using the chiral Sc(III) catalyst (10 mol%), which was prepared from 2,6-bis[(4S)-4-isopropyl-2-oxazolin-2-yl]pyridine and Sc(OTf)3, in reasonable yield (60 - 70%).
- Suga, Hiroyuki,Takemoto, Haruka,Kakehi, Akikazu
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- Syntheses of templates derived from pyrrolidine trans-lactams as potential serine protease inhibitors
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The synthesis of templates derived from pyrrolidine trans-lactams as shown in the graphic is described.
- Macdonald, Simon J.F.,Inglis, Graham G.A.,Bentley, Deborah,Dowle, Michael D.
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- A facile approach to α,β-unsaturated lactams by ring-closing metathesis
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[MediaObject not available: see fulltext.]A facile and efficient strategy for the synthesis of α,β-unsaturated lactams through ring-closing metathesis of easily prepared diene amides is being reported here. Reaction conditions were optimized for metathetic cyclization of diene amides to obtain five- to sevenmembered unsubstituted and β-substituted α,β-unsaturated lactams in good to excellent yield.
- Gondal, Humaira Yasmeen,Buisson, Didier
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p. 183 - 191
(2016/07/28)
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- N-Substituted tertiary and O-substituted quaternary carbon stereogenic centers by site-, diastereo- and enantioselective vinylogous Mannich reactions
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A readily accessible small-molecule phosphine, derived from commercially available starting materials such as an enantiomerically pure amino acid, serves as the precursor to a Ag-based chiral complex that can be prepared and used in situ to promote a vari
- Silverio, Daniel L.,Fu, Peng,Carswell, Emma L.,Snapper, Marc L.,Hoveyda, Amir H.
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supporting information
p. 3489 - 3493
(2015/06/02)
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- Organocatalytic asymmetric direct vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to nitroolefins
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The first organocatalytic enantioselective direct vinylogous Michael reaction of α,β-unsaturated γ-butyrolactam to nitroolefins is developed using cinchona alkaloids as the catalysts. Both product enantiomers are accessible with moderate to good enantioselectivity.
- Choudhury, Abhijnan Ray,Mukherjee, Santanu
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supporting information; experimental part
p. 7313 - 7320
(2012/10/07)
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- Mild and rapid hydroxylation of aryl/heteroaryl boronic acids and boronate esters with N-oxides
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Aryl and heteroaryl boronic acids and boronate esters are rapidly, often within minutes, transformed into the corresponding phenols by N-oxides in an open flask at ambient temperature. This transformation has broad compatibility with a variety of functional groups.
- Zhu, Chen,Wang, Rui,Falck
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supporting information; experimental part
p. 3494 - 3497
(2012/08/28)
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- Catalytic, asymmetric vinylogous Mukaiyama aldol reactions of pyrrole- and furan-based dienoxy silanes: How the diene heteroatom impacts stereocontrol
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Denmark's chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base-Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole- and furan-based dienoxy silanes with aromatic and heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to a variety of d-hydroxylated g-butenolide-type frameworks with high efficiency and valuable margins of regio-, diastereo-, and enantioselectivity. Notably, the nature of the heteroatom within the vinylogous dienoxy silane donor heavily impacts the diastereocontrol, with syn-configured aldol adducts emerging from pyrroles bearing electron- withdrawing N-protecting groups (Boc, Ts, and Cbz) and anti-configured adducts prevailing when furan- or N-alkyl/alkenylpyrrole donors are involved.
- Curti, Claudio,Ranieri, Beatrice,Battistini, Lucia,Rassu, Gloria,Zambrano, Vincenzo,Pelosi, Giorgio,Casiraghi, Giovanni,Zanardi, Franca
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supporting information; experimental part
p. 2011 - 2022
(2010/11/17)
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- Vicarious silylative mukaiyama aldol reaction: A vinylogous extension
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(Chemical Equation Presented) A vinylogous, silylative, and direct variant of the venerable Mukaiyama aldol reaction has been developed. Exploiting N-Boc-pyrrol-2(5H)-one as the conjugate donor, several aldehyde and ketone acceptors were scrutinized under
- Curti, Claudio,Sartori, Andrea,Battistini, Lucia,Rassu, Gloria,Burreddu, Paola,Zanardi, Franca,Casiraghi, Giovanni
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p. 5446 - 5451
(2008/12/21)
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- Synthetic studies on the CDEF ring system of lactonamycin
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Both (1) furan-maleimide Diels-Alder cycloaddition reaction and (2) furan-benzyne cycloaddition, Suzuki cross-coupling, boron-mediated aldol, and electrophilic aromatic substitution reactions were examined for the construction of the CDEF ring system of l
- Le Vézou?t, Ronan,White, Andrew J.P.,Burrows, Jeremy N.,Barrett, Anthony G.M.
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p. 12252 - 12263
(2007/10/03)
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- Redox isomerization of allylic alcohols and amides using Grubbs' catalyst
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Commercially available Grubbs' catalyst was found to catalyze the redox isomerization of allylic alcohols and amides under mild conditions.
- Greenwood,Parsons,Young
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p. 223 - 228
(2007/10/03)
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- An efficient scalable process for the synthesis of N-Boc-2-tert-butyldimethylsiloxypyrrole
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A safe, reliable and scalable process for the preparation of N-Boc-2-tert-butyldimethylsiloxy-pyrrole (TBSOP) is described. In a three-step, one-pot sequence (±)-4-amino-3-hydroxybutyric acid was converted to N-Boc-4-hydroxy-2-pyrrolidinone. This stable crystalline product was isolated by filtration directly from the reaction mixture. Dehydration followed by enolization and silylation produced the target compound without the need for chromatographic purification. The process was demonstrated in the pilot plant to make multikilogram quantities of material in 85% overall yield.
- Tian, Zhenping,Rasmussen, Michael,Wittenberger, Steven J.
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p. 416 - 418
(2013/09/06)
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- Homochiral α,β-Unsaturated γ-Lactams: Versatile Templates
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The enantiomerically pure crystalline α,β-unsaturated γ-lactams 4 and 5 have been synthesized by utilizing 2,3-O-isopropylidene-D-glyceraldehyde (3) as chiral source and novel N-tert-butoxycarbonyl-2-(tert-butyldimethylsiloxy)pyrrole (TBSOP) as a four car
- Rassu, Gloria,Casiraghi, Giovanni,Spanu, Pietro,Pinna, Luigi,Fava, Giovanna Gaspari,et al.
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p. 1035 - 1048
(2007/10/02)
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