<sup>13</sup>C nuclear magnetic resonance spectra of methoxycyclohexane derivatives. Rotamer populations about C–OMe bonds as indicated by<sup>13</sup>C chemical shifts of methoxy- and ring-carbons and<sup>3</sup>J<sub>C,H</sub>coupling constants
作者:Alan H. Haines、Mohammad Seyedi Shandiz
DOI:10.1039/p19810001671
日期:——
Methoxy 13C chemicalshifts in methoxycyclohexanederivatives may be rationalized in terms of rotamerpopulationsabout the C–OMe bond and δ1-effects caused by steric interaction of the methoxy-group with substituents at the neighbouring 2- and 6-positions. Information on rotamerpopulations is obtained also from the 13C chemicalshifts of C-2 and C-6, and from the three-bond coupling between the proton
Methyl-triisopropoxy-titanium, a highly selective nucleophilic methylating reagent. Preliminary Communication
作者:Beat Weidmann、Dieter Seebach
DOI:10.1002/hlca.19800630839
日期:1980.12.10
Replacement of lithium or magnesium by titanium can furnish nucleophilic organometallic reagents of high selectivity as exemplified by the title compound 1 (see Tables 1–3).
钛替代锂或镁可以提供具有高选择性的亲核有机金属试剂,如标题化合物1所示(请参见表1-3)。
Highly Efficient Conversion of Alcohols to Isocyanides
作者:Yoshikazu Kitano、Kazuhiro Chiba、Masahiro Tada
DOI:10.1055/s-2001-11423
日期:——
Treatment of tertiary alcohols with silver salts (AgClO4, AgBF4, or AgOTf) and trimethylsilyl cyanide (TMSCN), followed by hydrolysis, directly affords excellent yields of corresponding isocyanides. This reaction proceeds selectively with tertiary alcohols in the presence of primary and secondary alcohols.
Unprecedented stereoselectivity in the addition of organoiron(II) reagents to cyclohexanone derivatives
作者:Manfred T. Reetz、Stephan Stanchev
DOI:10.1039/c39930000328
日期:——
Various organoiron(II) reagents undergo Grignard-type additions to substituted cyclohexanone derivatives, C–C bond formation occurring stereoselectively from the equatorial direction (97–100% selectivity).
selectivity. trans-Oxazolidinones were prepared from acyclic secondary N-mesyloxycarbamates using Rh2(oct)4. The selectivity was reverted with a cytoxazone N-mesyloxycarbamate precursor using large chiralrhodium(II) carboxylate complexes, affording the corresponding cis-oxazolidinone. This orthogonal selectivity was used to achieve the formal synthesis of (−)-cytoxazone.