Long‐range J_CH heteronuclear coupling constants in cyclopentane derivatives

Abstract

Detailed measurements of long-range heteronuclear spin-spin coupling constants, especially (2, 3)J(CH) spin-spin couplings for various cyclopentane derivatives, are reported. The measurements are based on a 2D heteronuclear correlation experiment named G-BIRD(R, X)-CPMG-HSQMBC.

Analyses, extensions and comparison of three experimental schemes for measuring (nJCH+DCH)-couplings at natural abundance

“…The LR-CAHSQC [27] with a slight modification using composite pulses [28] and the socalled BIRD r,X -CPMG-HSQMBC [29]. Sequences for both experiment types are shown in Fig.…”

“…Three experiment types are explored in the following: The intensity and multiplet pattern based coupling measurement out of an HMBC with a corresponding reference HSQC [26], the pattern-based coupling extraction from CPMG-type transfer experiments [27][28][29], and the displacement based coupling determination from IPAP-type HSQC-TOCSY experiments [30,31].…”

Stereochemistry of cyclopentane derivatives from 2, 3JCH dependence on dihedral angle (θ HCCX)

“…In this context, we have already reported the detailed measurement of longrange heteronuclear scalar spin-spin coupling constants ( 2,3 J CH ) for various cyclopentanes. [11,12] Our investigation is also concerned with the search for a correlation between the magnitude of the observed 3 J CH couplings and the calculated dihedral angles between the coupled nuclei (θ H-C-C-C) and the observed 2 J CH couplings and the calculated dihedral angles between the coupled hydrogen and the neighboring oxygen substituent (θ H-C-C-O) in cyclopentanes 1-7b.…”

P.E.HSQC: A simple experiment for simultaneous and sign-sensitive measurement of (1JCH+DCH) and (2JHH+DHH) couplings

“…Only the SPITZE-HSQC [19] with HEHAHA transfer steps avoids this homonuclear antiphase evolution due to isotropic mixing conditions present during transfer periods with the disadvantage of a very limited bandwidth. In principle, homonuclear antiphase evolution could also be compensated by the application of CPMG-type pulse trains with homonuclear isotropic mixing conditions during the INEPT-type transfer steps [25][26][27][28][29], but this approach is power consuming and the common 13 C-bandwidth of %130 ppm for 1 H, 13 C one-bond correlation experiments cannot be covered by conventional probeheads at high-field spectrometers.…”