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Search for "Grignard reagents" in Full Text gives 98 result(s) in Beilstein Journal of Organic Chemistry.

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

  • Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

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  • four-component reaction through a methyleneaziridine ring-opening process has been developed for the synthesis of α-aminophosphonates [76]. Thus, the one-pot reaction between methyleneaziridines 173, Grignard reagents 174, alkyl halides 175 and dialkyl phosphonates in the presence of CuI afforded
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Published 21 Jun 2016

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

  • Jaroslav Padevět,
  • Marcus G. Schrems,
  • Robin Scheil and
  • Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

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  • to the threonine methyl ester or N-protected derivatives were also briefly investigated, but failed. Grignard addition to the chloro amide 11 was not attempted because earlier studies with chloro amide 15 had shown that an undesired β-lactam 16 was formed upon treatment with Grignard reagents (Scheme
  • asymmetric catalysis. A further notable feature of these ligands is their flexible synthesis, which allows easy variation of the substituent at the stereogenic center. Using different Grignard reagents in the addition to the ester group of a late stage intermediate, an array of tertiary alcohol derivatives
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Published 13 Jun 2016

One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

  • Gastón Silveira-Dorta,
  • Sergio J. Álvarez-Méndez,
  • Víctor S. Martín and
  • José M. Padrón

Beilstein J. Org. Chem. 2016, 12, 957–962, doi:10.3762/bjoc.12.94

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  • aldehydes. It comprises the one-pot sequential reduction to aldehyde with DIBAL-H at −78 °C and subsequent in situ addition of Grignard reagents. Remarkably, our method is friendly with serine and threonine derivatives without the requisite to protect the β-hydroxy group. With this tool in hand, we thought
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Published 12 May 2016

Recent advances in copper-catalyzed asymmetric coupling reactions

  • Fengtao Zhou and
  • Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

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  • primary allyl chlorides to react with alkylborane (alkyl-9-BBN) for the generation of a quaternary carbon stereogenic center bearing three sp3-alkyl groups and a vinyl group with an ee up to 90% (Scheme 29). Cu-catalyzed enantioselective allylic substitutions with Grignard reagents Transition metal
  • allyl Grignard reagents with allyl bromides, leading to chiral 1,5-dienes in good yield and with high enantioselectivity (Scheme 30). Cu-catalyzed enantioselective allylic substitutions with silylboronates Enantioenriched allylsilanes are very useful building blocks in synthetic organic chemistry [76
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Published 15 Dec 2015

Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

  • Thibault E. Schmid,
  • Sammy Drissi-Amraoui,
  • Christophe Crévisy,
  • Olivier Baslé and
  • Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

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  • diethylzinc proceeded at a typical catalyst loading of 5 mol %, and afforded the 1,6-adduct. Among the ligand series, L4 proved to form the most efficient system, affording product 33 in 60% yield and 82% ee. With Grignard reagents Linear dienoates are another class of highly challenging extended Michael
  • acceptors, which were the focus of a work reported by Feringa and co-workers in 2008 [28]. In this study, the efficiency of ferrocene-based ligands was investigated for the addition of Grignard reagents onto ethyl sorbate, using CuBr·SMe2 as the copper source. Reversed Josiphos L8 was selected as the most
  • efficient ligand for this transformation, as a 1,6- vs 1,4-selectivity up to 99:1 could be achieved. The versatility of the catalytic system was assessed with a wide substrate scope featuring aliphatic, aromatic and functionalized dienoates 34 and various Grignard reagents. The reported products 35 were
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Published 03 Dec 2015

Half-sandwich nickel(II) complexes bearing 1,3-di(cycloalkyl)imidazol-2-ylidene ligands

  • Johnathon Yau,
  • Kaarel E. Hunt,
  • Laura McDougall,
  • Alan R. Kennedy and
  • David J. Nelson

Beilstein J. Org. Chem. 2015, 11, 2171–2178, doi:10.3762/bjoc.11.235

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  • used as the HCl or HBF4 salt combined with [Ni(COD)2] [15][16][17]. In addition, a [Ni(OAc)2]/ICy·HCl system was found to allow the cross-coupling of Grignard reagents with aryl ethers [18]. However, the identity of the active catalyst, which is formed in situ in these reactions, is as yet unknown, and
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Published 12 Nov 2015

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

  • Ya Lin Tnay,
  • Gim Yean Ang and
  • Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

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  • the construction of oxaspirocyclohexadienones as well as in the electrophilic cyanation of Grignard reagents with pivalonitrile as a CN source. Keywords: C–C bond cleavage; copper; ketimines; molecular oxygen; radical; Introduction Alkylideneaminyl radicals (iminyl radicals) have been utilized for
  • of Grignard reagents to carbonitriles followed by protonation as one of the methods for in situ generation of N–H ketimines, which were directly subjected to Cu-catalyzed aerobic reactions without further purification [54]. In this way, biaryl N–H ketimines generated from biaryl-2-carbonitriles were
  • applications of the copper-catalyzed aerobic C–C bond fission of iminyl radical species for the synthesis of oxaspirocyclohexadienones as well as the electrophilic cyanation of Grignard reagents using the readily available pivalonitrile as a CN source. Results and Discussion We further explored the reactivity
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Published 19 Oct 2015

An efficient synthesis of N-substituted 3-nitrothiophen-2-amines

  • Sundaravel Vivek Kumar,
  • Shanmugam Muthusubramanian,
  • J. Carlos Menéndez and
  • Subbu Perumal

Beilstein J. Org. Chem. 2015, 11, 1707–1712, doi:10.3762/bjoc.11.185

Graphical Abstract
  • associated with the lack of regioselectivity and difficult isomer separation [23]. Other methods for the synthesis of 2,3-disubsituted thiophenes include the reactions of (i) 1,4-dithiane-2,5-diol with nitroalkenes [24], activated nitriles [25] and cyanoacetamide [26]; (ii) 3-nitrothiophene with Grignard
  • reagents [27] and (iii) 3-bromo-2-silylthiophene with aldehydes [28]. The major drawback of these methods is that none of them allow the simultaneous introduction of 2-amino and 3-nitro substituents (see Scheme 1d for a representative example). Multiple bond-forming transformations [29][30][31] are very
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Published 22 Sep 2015

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF5-substituted phenylboronic esters and iodobenzenes

  • George Iakobson,
  • Junyi Du,
  • Alexandra M. Z. Slawin and
  • Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

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  • Grignard reagents is inefficient. On the other hand, Shibata and co-workers have recently reported the synthesis of 3,5-bis(pentafluorosulfanyl)phenylboronic acid from the corresponding aryl bromide, trimethyl borate and iPrMgBr [32]. Finally, Joliton and Carreira have recently shown efficient Ir-catalyzed
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Published 26 Aug 2015

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

  • Iris Binyamin,
  • Shoval Meidan-Shani and
  • Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

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  • ring opening of the corresponding oxaphospholanes is described. Two representative substrates: the phosphonate 2-ethoxy-1,2-oxaphospholane 2-oxide and the phosphinate 2-phenyl-1,2-oxaphospholane 2-oxide were reacted with various Grignard reagents to produce a single alkyl/aryl product. These products
  • may possess further functionalities in addition to the phosphorus center such as the γ-hydroxypropyl group which results from the ring opening and π-donor moieties such as aryl, allyl, propargyl and allene which originates from the Grignard reagent. Keywords: chirogenic phosphorus; Grignard reagents
  • compounds [26][38][39]. In our previous work, we investigated the reaction of 2-ethoxy-1,3,2-dioxaphospholane 2-oxide (2) with Grignard reagents, and showed that phosphonates were formed as single products via a regioselective endocyclic P–O bond cleavage [40][41][42]. In continuation of this work, we
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Published 30 Jul 2015

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

  • Marcus Baumann and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

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  • showcased the generation and use of organometallic species (i.e., Grignard reagents) in flow synthesis as well as in-line React-IR monitoring in order to precisely control the onset of late stage flow streams that are affected by dispersion effects thus marking the first use of this now commonly
  • consistent reagent delivery is crucial. In order to address these issues flow equipment utilising adapted peristaltic pumps have been developed and applied to several mesoscale syntheses utilising common organometallic reagents (i.e., n-BuLi, Grignard reagents, DIBAL-H) [106]. The pump design uses specific
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Published 17 Jul 2015

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

  • Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

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  • the auxiliary that locked the conformation of the molecule. The excess Grignard reagent would add to the double bond from the less sterically hindered side, thus leading to the diastereoselectivity. Note that when using Grignard reagents as nucleophiles in CA reactions, the possibility of the 1,2
  • the most common chiral auxiliaries that have been used. Like the Mukaiyama example, the Oppolzer auxiliary (4) was used in DCA reactions with Grignard reagents [36][37]. The advantages of using this auxiliary are that it is readily available from (−) or (+)-camphor-10-sulfonyl chloride, both the
  • reactions [33][39]. It has also been utilized in DCA reactions of α,β-unsaturated amides [40][41][42][43][44]. One of the first examples was published by Hruby and co-workers, where they added Grignard reagents, in the presence of a CuBr–(CH3)2S complex, to a series of α,β-unsaturated-N-alkenoyl-2
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Published 23 Apr 2015

One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

  • Joshua P. Barham,
  • Matthew P. John and
  • John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

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  • BrCCl3 and its byproduct CHCl3 [22] were responsible for poor organometallic reaction profiles. Generation of radical intermediates or carbenes upon reacting Grignard reagents or magnesium salts with BrCCl3 or CHCl3 are evidenced in the literature [38][39]. Initially, we took advantage of the
  • -quantitative (90%) conversion of 4a to 5a in 3 h (anhydrous conditions). According to the mechanism proposed by Stephenson for BrCCl3 [22], BrCH2CN forms MeCN as an inert product. Grignard additions were unaffected by traces of residual BrCH2CN and a selection of substrates (4a, 11a–13a) and Grignard reagents
  • facilitated full conversion of 4a to 5a in 2 h (Table 1). Here, MeCN/H2O (4:1) was chosen because MeCN forms an azeotrope with water [40] such that it could be easily dried by concentration. After dissolving resultant crude 5a in anhydrous MeCN and shielding from ambient light, alkyl, aryl and vinyl Grignard
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Published 12 Dec 2014

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

  • Lidija-Marija Tumir,
  • Marijana Radić Stojković and
  • Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

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  • various substituents, which were nicely summarized by Keller a decade ago [8]. We tried to survey the wide range of synthetic methods applied from 2000 on organizing them by similarity of reactants/catalysts or organic reactions; for instance the anionic ring-closure reactions using Grignard reagents
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Published 10 Dec 2014

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

  • Roman Matthessen,
  • Jan Fransaer,
  • Koen Binnemans and
  • Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

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  • carboxylic acids from CO2 under relatively mild conditions, reactive organometallic nucleophiles such as Grignard reagents can be used, generating a large amount of waste [21][22][23][24]. Electroreduction of CO2 can be a worthy alternative for these dangerous energy-intensive processes, replacing toxic or
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Published 27 Oct 2014

Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

  • Maroš Bella,
  • Bohumil Steiner,
  • Vratislav Langer and
  • Miroslav Koóš

Beilstein J. Org. Chem. 2014, 10, 1942–1950, doi:10.3762/bjoc.10.202

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  • simple alkyl or aryl branched-chain sugars involves the addition of Grignard reagents. In this regard, a wide variety of Grignard reagents have been added to the free or masked (as hemiacetal) carbonyl functionalities present in the molecule of a suitable fully O-protected saccharide, thereby making
  • that the application of these reagents favours the addition of Grignard reagents to carbonyl compounds to afford higher yields [20][21][22]. Since all attempts to separate and purify carbinols 4–7 using column chromatography were unsuccessful even after acetylation, their physical and spectral data are
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Published 20 Aug 2014

Preparation of phosphines through C–P bond formation

  • Iris Wauters,
  • Wouter Debrouwer and
  • Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

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  • ]. Reaction of organometallic reagents with halophosphines The reaction of an organometallic reagent with the P-atom of halophosphines is a classical method used for the synthesis of both alkenyl- and arylphosphines. The organometallic reagents are mostly Grignard reagents [136][137][138] or organolithium
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Published 09 May 2014

A new manganese-mediated, cobalt-catalyzed three-component synthesis of (diarylmethyl)sulfonamides

  • Antoine Pignon,
  • Erwan Le Gall and
  • Thierry Martens

Beilstein J. Org. Chem. 2014, 10, 425–431, doi:10.3762/bjoc.10.39

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  • -supported benzotriazole [7] with arylmagnesium reagents, addition of phenyllithium to selenoamides [8], addition of organometallic species [9][10][11][12][13][14][15][16][17][18][19][20][21] or arylboronic acids [22][23][24][25][26][27] to imines, reaction of organolithium and Grignard reagents with
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Published 17 Feb 2014

Cyclic phosphonium ionic liquids

  • Sharon I. Lall-Ramnarine,
  • Joshua A. Mukhlall,
  • James F. Wishart,
  • Robert R. Engel,
  • Alicia R. Romeo,
  • Masao Gohdo,
  • Sharon Ramati,
  • Marc Berman and
  • Sophia N. Suarez

Beilstein J. Org. Chem. 2014, 10, 271–275, doi:10.3762/bjoc.10.22

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  • managed. A major challenge for this work has been the handling of the tertiary phosphine precursors, which are pyrophoric and extremely air sensitive. 1-n-Butylphospholane and 1-n-butylphosphinane were synthesized by the reaction of n-butyldichlorophosphine [21] with the appropriate bis-Grignard reagents
  • reaction of dichlorophenylphosphine with the appropriate bis-Grignard reagents, BrMg(CH2)4MgBr and BrMg(CH2)5MgBr, respectively. The resulting five-membered cyclic 1-phenylphospholane was isolated in the same manner as was the 1-n-butylphospholane: i.e. by conversion with BH3·THF to give the air-stable 1
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Published 24 Jan 2014

Synthesis of novel derivatives of 5-hydroxymethylcytosine and 5-formylcytosine as tools for epigenetics

  • Anna Chentsova,
  • Era Kapourani and
  • Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 7–11, doi:10.3762/bjoc.10.2

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  • treatment with various Grignard reagents (methylmagnesium bromide, THF, 0 °C → room temperature, or vinylmagnesium bromide, THF, 0 °C → room temperature) and organolithium reagents (lithium (trimethylsilyl)acetylide, THF, −40 °C → −20 °C or lithium phenylacetylide, THF, −78 °C → −50 °C) (Scheme 2). These
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Published 03 Jan 2014

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

  • Mikko Passiniemi and
  • Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

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  • model (as shown in Scheme 10). Joullié observed that the more reactive Grignard reagents (e.g., PhMgBr or MeMgBr) give rise to kinetic anti-products via the non-chelation pathway [62]. Since these reagents are highly reactive, the reaction takes place before the metal has coordinated to any of the
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Published 26 Nov 2013

The chemistry of amine radical cations produced by visible light photoredox catalysis

  • Jie Hu,
  • Jiang Wang,
  • Theresa H. Nguyen and
  • Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

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  • strategy to bypass the iminium ions and use α-amino radicals such as 112 instead to construct C–N bonds. Treatment of N,N-acetal product 111 with Grignard reagents (Scheme 26, entry 1) or indoles in the presence of TsOH (Scheme 26, entry 2) provided nucleophilic substitution products at the α carbon. This
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Published 01 Oct 2013

Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

  • Brad M. Loertscher,
  • Yu Zhang and
  • Steven L. Castle

Beilstein J. Org. Chem. 2013, 9, 1179–1184, doi:10.3762/bjoc.9.132

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  • [27]. Epoxide 17 was then subjected to ring-opening reactions with vinyl Grignard reagents in the presence of various copper salts. Surprisingly, only trace amounts of the desired product were detected, with recovered starting material and multiple byproducts typically comprising the majority of the
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Published 18 Jun 2013

Camera-enabled techniques for organic synthesis

  • Steven V. Ley,
  • Richard J. Ingham,
  • Matthew O’Brien and
  • Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

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  • reactor has also been reported by Kappe and co-workers for the observation of arcing during the irradiation of a number of metal-solvent systems [49], such as during the formation of Grignard reagents [50], and to monitor stirring effects within the microwave chamber [51]. High-speed digital camera
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Published 31 May 2013

Efficient synthesis of β’-amino-α,β-unsaturated ketones

  • Isabelle Abrunhosa-Thomas,
  • Aurélie Plas,
  • Nishanth Kandepedu,
  • Pierre Chalard and
  • Yves Troin

Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52

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  • nucleophilic addition reaction of Grignard reagents to N-carbamoyl β-amino Weinreb amides (Scheme 2) [18]. Conjugate addition of (R)-N-benzyl-N-methylbenzylamide to methyl cinnamate under basic conditions led to β–aminoester 5 with high diastereoselectivity (dr >94%) [11][12]. Subsequent transformation of the
  • ester moiety to a Weinreb amide [18] followed by changing the nitrogen protecting group to a carbamate furnished the key intermediate 6, which could be further alkylated with Grignard reagents to give β’-amino protected α,β-enone 1 in good overall yield and high enantiomeric excess. As Grignard reagents
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Published 06 Mar 2013
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