Carbon‐13 NMR spectra of tetracyclododecanes: Evidence for upfield δ and ε steric effects

Abstract

"C NMR spectra of 36 endo-endo, exo-enúo and ex-xo tetracyclic fused norbornyl compounds are interpreted.Stereochemical influences on 'H and "C chemical shifts are compared and discussed. Only upfield S and E effects are observed.

Low viscous aminoalkyl‐phenyl‐silane with π–π interaction and its optimal SO2 capture condition

“…C‐5 on the phenyl group connected to Si of chloromethyldimethylphenylsilane moved to C‐5′. The reason is that the large substituent group has a strong steric compression and de‐shielding effect 21 . Furthermore, the synthesis of DTSMA has been reported in our previous work 15 .…”

“…strong steric compression and de-shielding effect. 21 Furthermore, the synthesis of DTSMA has been reported in our previous work. 15 Next, the purity of absorbents was measured by gas chromatography.…”

Evaluation of lipases in the desymmetrization of meso-exo-3,5-dihydroxymethylenetricyclo[5.2.1.0(2,6)]decane and the synthesis of chiral derivatives

“…9 Optically active aminooxy alcohols would appear to be very interesting building blocks in the search for novel biologically active compounds and the synthesis of such optically active derivatives by using a lipase-catalyzed acetylation has been described. 9 The goal of our research group over the last few years has been the study and application of constrained polycyclic compounds, from both a conformational and stereochemical viewpoint, 15 as well as in terms of their reactivity and enantiomeric resolution. 16 In this work we report the evaluation of various lipases for the desymmetrization of meso-exo-3,5-dihydroxymethylenetricyclo[5.2.1.0 2,6 ]decane in vinyl acetate and the preparation of derivatives as chiral building blocks, carrying functional groups in flexible chains on appropriate positions of the tricyclic framework.…”

On the mechanism of skeletal rearrangements in the acid catalysed acetylation of isodrin †

“…These pioneering studies established the basis for numerous works involving several aspects of modern chemistry, such as investigation of carbocations and intramolecular rearrangements, 4-8 steric compression, long-range and short-range interactions 9-13 as well as NMR spectroscopy. [14][15][16][17] Recently our group has demonstrated that the pentacyclo[5.4.1.0 3,10 .0 4,12 .0 5,9 ]dodecane derivatives, known as half-cage compounds, are interesting models for the development of methodologies for enantiomeric analysis in NMR spectroscopy using a mixture of chiral and achiral shift reagents, 18, 19 and for the development of an approach to determine the optimal position of a lanthanide ion in complexes formed by shift reagents with a substrate using the pseudocontact model 20 and the kinetic resolution of very hindered secondary alcohol that uses lipase from Candida rugosa. 21 Serious limitations in the studies of these strained systems are the low yields and the difficult purification of compounds.…”