0000000001303681
AUTHOR
Emmanuelle Rémond
Modular Hemisyntheses of Boronato- and Trifluoroborato-SubstitutedL-NHBoc Amino Acid and Peptide Derivatives
Modular hemisyntheses of boronato- and trifluoroborato-substituted amino acid and peptide derivatives by using Wittig and C–H iridium-catalyzed borylation as key reactions, are described. Amino ester precursors bearing an aromatic moiety on a lateral chain were prepared by reaction of a new L-NHBoc-amino acid Wittig reagent with the corresponding aromatic aldehydes. After esterification and hydrogenation, the borylation of amino esters was achieved with yields up to 82 % by using the catalysed reaction of bis(pinacolato) diborane reagent (B2Pin2) in the presence of an iridium complex. Interestingly, this iridium-catalyzed borylation was also performed with a dipeptide in 78 % yield. Finally…
Asymmetric addition of a nitrogen nucleophile to an enoate in the presence of a chiral phase-transfer catalyst: A novel approach toward enantiomerically enriched protected β-amino acids
A proof of concept for the asymmetric organocatalytic aza-Michael addition reaction of nitrogen nucleophiles with simple and readily available alkyl enoates as acceptor molecules in the presence of a chiral phase-transfer catalyst has been demonstrated. The desired enantiomerically enriched beta-amino acid derivatives were obtained in up to 86% yield and with enantioselectivities of up to 37% ee. (C) 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:202209, 2012; View this article online at . DOI 10.1002/hc.21004
ChemInform Abstract: Efficient Stereoselective Synthesis of Boron L-amino Acid Derivatives Using Wittig and Borylation Reactions
The stereoselective synthesis of a new classes of boronato- or trifluoroborato aminoacids and peptides was described using Wittig and C-H iridium borylation as key reactions. A trifluoroborato-thio...
Efficient Stereoselective Synthesis of Boron L-Amino Acid Derivatives Using Wittig and Borylation Reactions
The stereoselective synthesis of a new classes of boronato- or trifluoroborato aminoacids and peptides was described using Wittig and C-H iridium borylation as key reactions. A trifluoroborato-thio...
Stereoselective synthesis of unsaturated and functionalized L-NHBoc amino acids, using Wittig reaction under mild phase-transfer conditions.
The stereoselective synthesis of a new amino acid phosphonium salt was described by quaternization of melting triphenylphosphine with the γ-iodo NHBoc-amino ester, derived from L-aspartic acid. The deprotection of the carboxylic acid function to afford the phosphonium salt with a free carboxylic acid group was achieved by a palladium-catalyzed desallylation reaction. This phosphonium salt was used in the Wittig reaction with aromatic or aliphatic aldehydes and trifluoroacetophenone, under solid-liquid phase-transfer conditions in chlorobenzene and in the presence of K(3)PO(4) as weak base, to afford the corresponding unsaturated amino acids without racemization. Thus, the reaction with subs…
ChemInform Abstract: Efficient Synthesis of Quaternary and P-Stereogenic Phosphonium Triflates.
An efficient and general method for the preparation of achiral and chiral phosphonium salts is reported. This synthesis is based on the quaternization of phosphines and their derivatives with arynes generated in situ from 2-(trimethylsilyl)aryl triflates. This methodology is successfully applied to the synthesis of new valuable P-stereogenic phosphonium triflates.
Efficient Synthesis of (P-Chirogenic) o-Boronated Phosphines from sec-Phosphine Boranes
An efficient synthesis of boronated phosphines with an o-phenylene-bridge prepared from sec-phosphine boranes and using benzyne chemistry is reported. Successive reactions of sec-phosphine boranes with n-BuLi and 1,2-dibromobenzene, and then with boron reagents, afford the o-boronatophenylphosphine derivatives in 71% yields. The use of P-chirogenic sec-phosphine boranes leads to the free boronated phosphines with retention of configuration at the P-center after decomplexation. The reaction of P-chirogenic o-boronatophenylphosphine with KHF2 affords the corresponding trifluoroborated phosphine with ee >98%.
ChemInform Abstract: Modular Hemisyntheses of Boronato- and Trifluoroborato-Substituted L-NHBoc Amino Acid and Peptide Derivatives.
Modular hemisyntheses of boronato- and trifluoroborato-substituted amino acid derivatives are achieved based on the reaction of Wittig reagent (I) with aldehydes followed by Ir-catalyzed boronation.
ChemInform Abstract: o-(Hydroxyalkyl)phenyl P-Chirogenic Phosphines as Functional Chiral Lewis Bases.
The stereoselective synthesis of P-chirogenic phosphines bearing an o-hydroxyalkyl chain is described.
Efficient synthesis of quaternary and P-stereogenic phosphonium triflates
An efficient and general method for the preparation of achiral and chiral phosphonium salts is reported. This synthesis is based on the quaternization of phosphines and their derivatives with arynes generated in situ from 2-(trimethylsilyl)aryl triflates. This methodology is successfully applied to the synthesis of new valuable P-stereogenic phosphonium triflates.
o-(Hydroxyalkyl)phenyl P-Chirogenic Phosphines as Functional Chiral Lewis Bases
The stereoselective synthesis of P-chirogenic phosphines bearing an o-hydroxyalkyl chelating arm is described. The synthesis is based either on the hydroxyalkylation of P-chirogenic o-bromophenylphosphines (borane) or on their carbonatation and then reduction. The hydroxyalkylation with benzaldehyde or pivalaldehyde affords a mixture of epimers which are isolated by chromatography and characterized by their X-ray structures. Preliminary assays of free P-chirogenic o-(hydroxyalkyl)phenyl phosphines, as new functional Lewis bases in catalyzed asymmetric aza-MBH reaction, lead to β-aminoester derivatives with ee values up to 74%.
P-chirogenic organocatalysts: application to the aza-Morita–Baylis–Hillman (aza-MBH) reaction of ketimines
The P-chirogenic organocatalysts were found to promote the enantioselective aza-Morita-Baylis-Hillman reaction of ketimines derived from acyclic α-keto esters. In the P-chirogenic organocatalyzed aza-MBH reactions, α,α-disubstituted α-amino acid derivatives were obtained in high yields with high enantioselectivities (up to 97% ee).
CCDC 945143: Experimental Crystal Structure Determination
Related Article: Shinobu Takizawa, Emmanuelle Rémond, Fernando Arteaga Arteaga, Yasushi Yoshida, Vellaisamy Sridharan, Jérôme Bayardon, Sylvain Jugé, Hiroaki Sasai|2013|Chem.Commun.|49|8392|doi:10.1039/C3CC44549F
CCDC 937024: Experimental Crystal Structure Determination
Related Article: Emmanuelle Rémond, Jérôme Bayardon, Shinobu Takizawa, Yoann Rousselin, Hiroaki Sasai, and Sylvain Jugé|2013|Org.Lett.|15|1870|doi:10.1021/ol400515e
CCDC 937026: Experimental Crystal Structure Determination
Related Article: Emmanuelle Rémond, Jérôme Bayardon, Shinobu Takizawa, Yoann Rousselin, Hiroaki Sasai, and Sylvain Jugé|2013|Org.Lett.|15|1870|doi:10.1021/ol400515e
CCDC 937025: Experimental Crystal Structure Determination
Related Article: Emmanuelle Rémond, Jérôme Bayardon, Shinobu Takizawa, Yoann Rousselin, Hiroaki Sasai, and Sylvain Jugé|2013|Org.Lett.|15|1870|doi:10.1021/ol400515e
CCDC 1053706: Experimental Crystal Structure Determination
Related Article: Jérôme Bayardon , Julie Bernard , Emmanuelle Rémond , Yoann Rousselin , Raluca Malacea-Kabbara , and Sylvain Jugé|2015|Org.Lett.|17|1216|doi:10.1021/acs.orglett.5b00167
CCDC 937023: Experimental Crystal Structure Determination
Related Article: Emmanuelle Rémond, Jérôme Bayardon, Shinobu Takizawa, Yoann Rousselin, Hiroaki Sasai, and Sylvain Jugé|2013|Org.Lett.|15|1870|doi:10.1021/ol400515e
CCDC 1053707: Experimental Crystal Structure Determination
Related Article: Jérôme Bayardon , Julie Bernard , Emmanuelle Rémond , Yoann Rousselin , Raluca Malacea-Kabbara , and Sylvain Jugé|2015|Org.Lett.|17|1216|doi:10.1021/acs.orglett.5b00167
CCDC 1053708: Experimental Crystal Structure Determination
Related Article: Jérôme Bayardon , Julie Bernard , Emmanuelle Rémond , Yoann Rousselin , Raluca Malacea-Kabbara , and Sylvain Jugé|2015|Org.Lett.|17|1216|doi:10.1021/acs.orglett.5b00167