β-Silylated Homopropargylic Amines via the Asymmetric Allenylboration of Aldimines
摘要:
The asymmetric synthesis of alpha-trimethylsilylpropargylic carbamines (7) through the addition of allenylboranes 4 to N-H aldimines is reported. The insertion of TMSCHN2 into enantiomerically pure B-alkynyl-10-TMS-9-borabicyclo[3.3.2]decanes 3 followed by a sterically driven 1,3-suprafacial borotropic shift proceeds with complete stereospecificity to produce 4 in diastereomerically and enantiomerically pure form. These reagents give 7 (51-85%, syn/anti > 99%, 92-9% ee) permitting the recovery of 8 (53-63%). Allenylboranes 4 also provide a convenient route to optically pure allenylsilanes 13 (55-94%) through their protonolysis.
Studies on the Bisoxazoline- and (−)-Sparteine-Mediated Enantioselective Addition of Organolithium Reagents to Imines
作者:Scott E. Denmark、Noriyuki Nakajima、Cory M. Stiff、Olivier J.-C. Nicaise、Michael Kranz
DOI:10.1002/adsc.200800017
日期:2008.5.5
The enantioselective addition of organolithiumreagents to N-anisyl aldimines promoted by chiral bisoxazolines and (-)-sparteine as external ligands is described. This reaction proceeds readily with a wide range of aldimine substrates (aliphatic, aromatic, olefinic) and organolithium nucleophiles (Me, n-Bu, Ph, vinyl) in excellent yields (81-99%) and with high enantioselectivities (up to 95.5:4.5 er)
Addition of Highly Polarized Organometallic Compounds to
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‐Butanesulfinyl Imines in Deep Eutectic Solvents under Air: Preparation of Chiral Amines of Pharmaceutical Interest
作者:Luciana Cicco、Antonio Salomone、Paola Vitale、Nicolás Ríos‐Lombardía、Javier González‐Sabín、Joaquín García‐Álvarez、Filippo M. Perna、Vito Capriati
DOI:10.1002/cssc.202001142
日期:2020.7.22
primary amines after quantitatively removing the sulfinyl group. The practicality of the method is further highlighted by proceeding at ambient temperature and under air, with very short reaction times (2 min), enabling the preparation of diastereoisomeric sulfinamides in very good yields (74–98 %) and with a broad substrate scope, and the possibility of scaling up the process. The method is demonstrated
Synthesis and Applications of Chiral Organoboranes Generated from Sulfonium Ylides
作者:Varinder K. Aggarwal、Guang Yu Fang、Andreas T. Schmidt
DOI:10.1021/ja043632k
日期:2005.2.1
The reactions of aryl-stabilized sulfonium ylides with trialkyl/triarylboranes have been investigated. Clean monohomologation of the boranes with only a small amount of the higher homologation products (<10%) was observed. The homologation products were isolated as the alcohols (treatment with H2O2/NaOH) and amines (treatment with NH2OSO3H). Although the reactions were conveniently conducted at 5 degrees
Enantioselective syntheses of α-phenylalkanamines via intermediate addition of Grignard reagents to chiral hydrazones derived from (R)-(−)-2-aminobutan-1-ol
作者:Patricia Bataille、Michel Paterne、Eric Brown
DOI:10.1016/s0957-4166(98)00217-1
日期:1998.6
The hydrazine (R)-(−)-28 was obtained in four steps from 2-aminobutan-1-ol (R)-(−)-11, and reacted with benzaldehyde to give the hydrazone (R)-(−)-29. Nucleophilic addition of various alkyl Grignardreagents to the latter yielded the corresponding trisubstituted hydrazines (R,R)-30a–g in 70–89% yields and having d.e.s=100% (1H and 13C NMR). Catalytic hydrogenolysis of these hydrazines afforded the
从2-氨基丁-1-醇(R)-(-)- 11通过四个步骤获得肼(R)-(-)- 28,并与苯甲醛反应得到the(R)-(-)-。29。向后者亲核添加各种烷基格氏试剂可得到相应的三取代肼(R,R)-30a - g,产率为70-89%,des = 100%(1 H和13 C NMR)。这些肼的催化氢解反应提供了相应的(R)-(+)-α-苯基链烷胺(R)-(+)- 31a – g ee = 90–92%(手性GPC)。
Catalytic Asymmetric Synthesis of β-Sultams as Precursors for Taurine Derivatives
作者:Marian Zajac、René Peters
DOI:10.1002/chem.200900496
日期:2009.8.17
2‐pyridylsulfonyl imines derived from non‐activated aromatic aldehydes employing Yb(OTf)3 as Lewis acid cocatalyst. The synthetic value of the strained enantioenriched β‐sultams was demonstrated by smooth nucleophilic ring opening reactions with O‐, N‐ and C‐nucleophiles yielding a variety of acyclic β‐aminosulfonyl (taurine) derivatives (sulfonates, sulfonamides, sulfones) without racemization or epimerization