Alkylmetal asymmetric reduction. 18. Starting materials in the preparation of new chiral reducing agents: synthetic approach to primary alkyl halides derived from (+)-camphor

Falorni, Massimo; Lardicci, L.; Giacomelli, Giampaolo

doi:10.1021/jo00376a045

Cited by 30 publications

(14 citation statements)

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“…Collidine hydrochloride was dried prior to use by gentle heating under vacuum. The following compounds were purchased, prepared according to literature procedures, or have already been described in the literature: 1 ,28 2 ,28 3 ,29 7 ,14 8 ,16 9 ,16 10 ,17 13, 15 ,30 16 ,31 18 ,32 19, 21, 23, 25 ,33 26 ,34 28 ,35 31 ,35 33 ,36 36 36…”

Section: Methodsmentioning

confidence: 99%

“…(1,7,7‐Trimethyl‐bicyclo[2.2.1]hept‐2‐yl)‐methanol (26) : Table 6 , entry 1 : According to GP 1 25 (166 mg, 1.0 mmol), 1,4‐cyclohexadiene (385 mg, 4.8 mmol), [Cp 2 TiCl 2 ] (25 mg, 0.1 mmol), zinc dust (98 mg, 1.5 mmol) and collidine hydrochloride (237 mg, 1.5 mmol) in THF (10 mL) for 19 h. Silica gel chromatography (CH:EE 8:1) gave 26 (91 mg, 55 %) as 57:43 mixture of diastereoisomers. The major isomer was assigned as exo by comparison of the spectra with those reported in the literature 34…”

Section: Methodsmentioning

confidence: 99%

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Reagent‐Controlled Stereoselectivity in Titanocene‐Catalyzed Epoxide Openings: Reductions and Intermolecular Additions to α,β‐Unsaturated Carbonyl Compounds

Gansäuer

Bluhm

Rinker

et al. 2003

Chemistry A European J

113

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The generation and addition reactions of metal bound radicals derived from normal and meso epoxides by electron transfer from titanocene(III) reagents is described. The control of enantioselectivity and diastereoselectivity of these transformations is investigated by variation of the ligands of the metal complex. The reaction can lead to unprecedented and highly selective reactions, in which synthetically useful alcohols may be prepared. The synthesis presented also circumvents the use of toxic metals. Another advantage is that there is no loss of two functional groups as usually observed in reductive radical chain reactions.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Reagent‐Controlled Stereoselectivity in Titanocene‐Catalyzed Epoxide Openings: Reductions and Intermolecular Additions to α,β‐Unsaturated Carbonyl Compounds

Gansäuer

Bluhm

Rinker

et al. 2003

Chemistry A European J

113

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“…However, applying an additional 0.5 eq of the Mitsunobu reagents (Method B) resulted in further improvement of the yield of aziridines 9 and 10 (Table 1). In an attempted exchange of the hydroxyl in 1 and 2 into the corresponding bromo-compounds using the Appel reaction [26] (2 eq of CBr 4 and PPh 3 , then K 2 CO 3 ), we again obtained aziridines 8 (a known compound [27]) and 9. The products were the same as those obtained in the Mitsunobu reaction, so they were also formed by the direct internal substitution of the oxyphosphonium group by the secondary amine.…”

Section: Synthesis Of Aziridinesmentioning

confidence: 99%

“…The synthesis of aziridines was performed according to a modified literature procedure [26]. Method A: Into the solution of the appropriate amino alcohol (1 eq, 0.5 mmol) and triphenylphosphine (1.5 eq 0.75 mmol, 197 mg) in the dry ether in an ice-water bath under an argon atmosphere, was slowly added diethyl azodicarboxylate (1.5 eq 0.75 mmol, 116 µL) via syringe.…”

Section: General Procedures For the Synthesis Of Aziridinesmentioning

confidence: 99%

Regioselective and Stereodivergent Synthesis of Enantiomerically Pure Vic-Diamines from Chiral β-Amino Alcohols with 2-Pyridyl and 6-(2,2′-Bipyridyl) Moieties

2020

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In this report, we describe the synthetic elaboration of the easily available enantiomerically pure β-amino alcohols. Attempted direct substitution of the hydroxyl group by azido-functionality in the Mitsunobu reaction with hydrazoic acid was inefficient or led to a diastereomeric mixture. These outcomes resulted from the participation of aziridines. Intentionally performed internal Mitsunobu reaction of β-amino alcohols gave eight chiral aziridines in 45–82% yield. The structural and configuration identity of products was confirmed by NMR data compared to the DFT calculated GIAO values. For 1,2,3-trisubstituted aziridines slow configurational inversion at the endocyclic nitrogen atom was observed by NMR at room temperature. Moreover, when aziridine was titrated with Zn(OAc)2 under NMR control, only one of two N-epimers directly participated in complexation. The aziridines underwent ring opening with HN3 to form the corresponding azido amines as single regio- and diastereomers in 90–97% yield. Different results were obtained for 1,2-disubstituted and 1,2,3-trisubstituted aziridines. For the later aziridines ring closure and ring opening occurred at different carbon stereocenters, thus yielding products with two inverted configurations, compared to the starting amino alcohol. The 1,2-disubstituted aziridines produced azido amines of the same configuration as the starting β-amino alcohols. To obtain a complete series of diastereomeric vic-diamines, we converted the amino alcohols into cyclic sulfamidates, which reacted with sodium azide in SN2 reaction (25–58% overall yield). The azides obtained either way underwent the Staudinger reduction, giving a series of six new chiral vic-diamines of defined stereochemistries.

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“…(S)-3-Azido-2-phenyl-1-propanol (9): A solution of compound E (0.2 g, 0.83 mmol), CBr 4 (0.38 g, 1.16 mmol) and PPh 3 (0.26 g, 0.99 mmol) in 40 mL CH 2 Cl 2 was stirred at room temperature for 24 h. 7 The solvent was removed in vacuo and the residue was filtered through a plug of silica gel in 10% EtOAc/hexanes. The filtrate was concentrated in vacuo and the residue (0.16 g, R f = 0.8 (25% EtOAc/hexane)) dissolved in 15 mL THF; 25 mg of 10% Pd/C was then added to the reaction mixture and the SI-10 reaction flask purged three times with H 2 .…”

Section: Phmentioning

confidence: 99%

Asymmetric Schmidt Reaction of Hydroxyalkyl Azides with Ketones.

et al. 2003

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Diastereoselective syntheses Diastereoselective syntheses O 0031Asymmetric Schmidt Reaction of Hydroxyalkyl Azides with Ketones. -An asymmetric equivalent of the Schmidt reaction is developed based on in situ tethering allowing for stereocontrolled ring expansion of symmetrical cyclohexanones. The study is presented in continuation of previously published investigations. -(SAHASRABUDHE, K.; GRACIAS, V.; FURNESS, K.; SMITH, B. T.; KATZ, C. E.; REDDY, D. S.; AUBE*, J.; J. Am. Chem. Soc. 125 (2003) 26, 7914-7922; Dep. Med. Chem., Univ. Kans., Lawrence, KS 66045, USA; Eng.) -Nuesgen 46-031 2003 Diastereoselective syntheses

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Alkylmetal asymmetric reduction. 18. Starting materials in the preparation of new chiral reducing agents: synthetic approach to primary alkyl halides derived from (+)-camphor

Cited by 30 publications

References 1 publication

Reagent‐Controlled Stereoselectivity in Titanocene‐Catalyzed Epoxide Openings: Reductions and Intermolecular Additions to α,β‐Unsaturated Carbonyl Compounds

Reagent‐Controlled Stereoselectivity in Titanocene‐Catalyzed Epoxide Openings: Reductions and Intermolecular Additions to α,β‐Unsaturated Carbonyl Compounds

Regioselective and Stereodivergent Synthesis of Enantiomerically Pure Vic-Diamines from Chiral β-Amino Alcohols with 2-Pyridyl and 6-(2,2′-Bipyridyl) Moieties

Asymmetric Schmidt Reaction of Hydroxyalkyl Azides with Ketones.

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