Dihedral Angular Dependence of H—N—C—H Coupling Constants. Protonated Amines in Trifluoroacetic Acid

Fraser, Robert R.; Renaud, Roger N.; Saunders, John K.; Wigfield, Yuk Y.

doi:10.1139/v73-363

Cited by 24 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11 Hz. The latter value suggests a high HCNH dihedral angle in an anti positioning of the proton, following an extension of the Karplus law . From this observation, we can infer that the configuration of nitrogen is R .…”

Section: Resultsmentioning

confidence: 55%

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

et al. 2011

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 55%

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

et al. 2011

View full text Add to dashboard Cite

show abstract

“…This feature could be linked to the rigidity of the N ‐alkyl substituent that would get more important close to the B−N backbone thus hindering the rotation around the ‐CH 2 ‐CH 2 ‐ bonds. Related to this, the 1 H‐ 1 H COSY NMR spectrum displays distinct correlations between pairs of vicinal methylenic protons within the alkyl chain due to the well‐known dependence of the 3 J HH coupling constant on the HCCH dihedral angle [9] …”

Section: Resultsmentioning

confidence: 89%

Uncatalyzed Formation of Polyaminoboranes from Diisopropylaminoborane and Primary Amines: a Kinetically Controlled Polymerization Reaction

et al. 2021

View full text Add to dashboard Cite

Recently, we disclosed the uncatalyzed formation of polyaminoboranes (PABs) from monomeric diisopropylaminoborane (iPr2N−BH2) and primary amines (RNH2). Their structure is studied through a detailed multinuclear NMR study and their full spectroscopic characterization is presented revealing that N‐alkyl substituted PABs exhibit magnetically non‐equivalent methylenic protons in the close vicinity of the BN‐backbone. We also performed an in‐depth theoretical study of this global chemical process. The mechanism is fully apprehended and the strong influence of the temperature on the outcome of the reaction is unveiled. DFT‐calculations clearly show that the formation of the polyaminoboranes (RNH−BH2)n results from a kinetically controlled step‐growth polymerization reaction that can be globally viewed as a head‐to‐tail association process of the in situ generated transient monomeric monoalkylamino‐borane [RNH−BH2].

show abstract

“…The δ 41.00 and 41.63 values for the N -methyl carbon in the respective minor D 2 O and major CD 2 Cl 2 species clearly point to similar equatorial dispositions of this substituent. Placement of N + in the coupling path reduces the magnitudes of vicinal coupling constants involving N -H .…”

Section: Discussionmentioning

confidence: 99%

Solution and Solid-State Conformational and Structural Analysis of the N-Methyl Derivatives of (±)-threo-Methylphenidate, (±)-erythro-Methylphenidate, and (±)-threo-p-Methyl-methylphenidate Hydrochloride Salts

Glaser¹,

Adin²,

Shiftan³

et al. 1998

J. Org. Chem.

View full text Add to dashboard Cite

The conformational preferences of N-methyl derivatives of the dopamine reuptake blocker threo-methylphenidate [Ritalin] and the p-methyl analogue were determined in the solid state and in solution and that of the erythro isomer in solution. The solid-state structures of (±)-threo-N-methyl-α-phenyl-2-piperidineacetic acid methyl ester hydrochloride [(±)-threo-N-methyl-methylphenidate hydrochloride] (2) and (±)-threo-N,p-dimethyl-α-phenyl-2-piperidineacetic acid methyl ester hydrochloride (5) were determined by single crystal X-ray diffraction analysis. (±)-2 underwent spontaneous resolution to give crystalline chiral plates containing two independent molecules in the asymmetric ring, and at each site there is a disorder involving the N-methylpiperidinyl ring methylene and methyl carbon atoms with a 0.710(7):0.290(7) ratio of occupancy factors. The two (2RS,3RS,4SR) major disordered molecules have similar structures consisting of a chair conformation for the piperidine ring with axial N-methyl and CH(Ph)COOMe groups. The two (2RS,3RS,4RS) minor molecules in the disorder also have similar structures and differ from the major ones by epimerization at nitrogen and inversion of the piperidine ring to afford an axial N-methyl group, and an equatorial CH(Ph)COOMe group. (±)-5 gave crystalline plates also containing diaxially disposed piperidinyl-ring substituents. Dissolution in D2O of either 2 or its erythro-epimer (3) each gives a 5:4 ratio of two species in which the major species exhibits an axial N-methyl group and an equatorial CH(Ph)COOMe group while the minor species has a diequatorial arrangement for both substituents. Both of the axial N-methyl threo or erythro major species in D2O are overwhelmingly conformationally biased in favor of an antiperiplanar H(2)···H(3) disposition and one piperidine ring invertomer. Dissolution of the threo or erythro epimers in CD2Cl2 gives the same axial N-methyl/equatorial CH(Ph)COOMe and diequatorially disposed species but now in a reversed ratio [respectively 3:20 for threo and 4:5 for erythro].

show abstract

Dihedral Angular Dependence of H—N—C—H Coupling Constants. Protonated Amines in Trifluoroacetic Acid

Cited by 24 publications

References 12 publications

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

Uncatalyzed Formation of Polyaminoboranes from Diisopropylaminoborane and Primary Amines: a Kinetically Controlled Polymerization Reaction

Solution and Solid-State Conformational and Structural Analysis of the N-Methyl Derivatives of (±)-threo-Methylphenidate, (±)-erythro-Methylphenidate, and (±)-threo-p-Methyl-methylphenidate Hydrochloride Salts

Contact Info

Product

Resources

About

Dihedral Angular Dependence of H—N—C—H Coupling Constants. Protonated Amines in Trifluoroacetic Acid

Cited by 24 publications

References 12 publications

Reaction of Chiral Secondary Amines with [(η5-C5Me5)MCl2]2(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

Reaction of Chiral Secondary Amines with [(η5-C5Me5)MCl2]2(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

Uncatalyzed Formation of Polyaminoboranes from Diisopropylaminoborane and Primary Amines: a Kinetically Controlled Polymerization Reaction

Solution and Solid-State Conformational and Structural Analysis of the N-Methyl Derivatives of (±)-threo-Methylphenidate, (±)-erythro-Methylphenidate, and (±)-threo-p-Methyl-methylphenidate Hydrochloride Salts

Contact Info

Product

Resources

About

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation

Reaction of Chiral Secondary Amines with [(η⁵-C₅Me₅)MCl₂]₂(M = Rh(III), Ir(III)): Cyclometalation with or without Dehydrogenation