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Festkörper‐ 13 C‐NMR‐Spektroskopie, 1. Titantetrachlorid‐Komplexe von Diketonen: Ihre Bedeutung für Hydrid‐Reduktionen und ihre Festkörper‐NMR‐Spektren
Author(s) -
Maier Güunther,
Seipp Ulrich,
Kalinowski HansOtto,
Henrich Markus
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270816
Subject(s) - chemistry , titanium tetrachloride , adduct , ketone , nuclear magnetic resonance spectroscopy , hydride , nmr spectra database , diketone , medicinal chemistry , chelation , proton nmr , tetrachloride , stereochemistry , titanium , polymer chemistry , crystallography , hydrogen , spectral line , inorganic chemistry , organic chemistry , physics , astronomy , tin
Solid‐state 13 C‐NMR Spectroscopy, 1. — Titanium Tetrachloride Complexes of Diketones: Their Importance for Hydride Reductions and Their Solid‐State NMR Spectra Herrn Prof. Christoph Rüchardt zum 65. Geburtstag gewidmet. The influence of titanium tetrachloride on the diastereoselectivity of hydride reductions of 1,2‐, 1,3‐, 1,4‐ and 1,5‐diketones has been studied. The effect is especially pronounced in the case of 1,3‐diketones, where the addition of titanium tetrachloride reverses the stereoselectivity. The assumption of a chelate of type 32 or 33 can be confirmed by several observations: β‐hydroxy ketone 7 and β‐benzyloxy ketone 9 show the same dependence on the stereochemical course as diketone 5a . This compound forms complex 34 , whose conformation is known by X‐ray structure determination. From the solid‐state 13 C‐NMR spectra of the TiCl 4 adducts it can be deduced that 7 forms chelate 42 , which is close to the assumed intermediate 32 . In the case of phenyl‐substituted substrates solid‐state 13 C‐NMR spectroscopy can also be used to differentiate between real chelates (coordination of TiCl 4 at the oxygen atoms of the carbonyl groups) and π complexes.