Correlated spectroscopy decoupled spectra

The proton-decoupled 13C NMR spectrum of pergolide mesylate indicates the presence of twenty carbons, which are further identified as four non-protonated carbons, six methine carbons, and ten methyl and methylene carbons via a Distortionless Enhancement by Polarization Transfer (DEPT) spectrum. The eight aromatic and olefinic carbon resonances in the 134 ppm to 106 ppm region have chemical shifts consistent with an indole structure (2). The H NMR spectrum contains four aromatic proton resonances, from 6.88 to 7.22 ppm, whose chemical shifts are also indicative of an indole-type structure. The assignment of these carbon and proton resonances were confirmed with IH correlation spectroscopy (CDSY) and 3C-1H heteronuclear correlation spectroscopy (HETCORR). The UV spectrum also indicates the presence of an indole chromophore. 

Two-Dimensional Proton Correlation Spectroscopy A two-dimensional coupling correlation NMR spectrum shows all the proton coupling relationships in a molecule in a single, although longer, experiment. This is more efficient than spin decoupling, which probes one relationship at a time and may require many experiments. 

Two-dimensional (2D) NMR spectroscopy has recently been used to make absolute tacticity assignments without any other supports.195-208 An early successful example is H COSY analysis of poly(vinyl alcohol).198,199 Figure 17 shows a broad-band decoupled H COSY spectrum of poly (vinyl alcohol)199 and illustrative assignments for the correlations between triad peaks of methine proton and tetrad peaks of methylene protons. Expected connectivities between triad and tetrad are as follows ... 

The product 2 was further characterized by multinuclear NMR spectroscopy. Homonuclear decoupling experiments show that the peaks at 2.4 and 0.74 ppm in the NMR spectrum are due to methylene and methyl protons on Ae nitrogen bound to boron, and the muMplets at 1.27 and 0.13 ate associated with methyl and methylene on aluminum. NMR spectrum reveals four main peaks at 37.8, 19.9,9.4, and -1.5 ppm. The shift correlation spectrum shows that... 

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