Preparation and Diels-Alder reactivity of ethyl-β-phenylsulfonylpropiolate

Ethyl-β-phenylsulfonylpropiolate ($\text{1b}$) is a reactive and highly regioselective dienophile in the Diels-Alder reaction.     

13C-NMR. Spectroscopy of Naturally Occurring Substances. XXXV. Labdanic diterpenes

A total carbon shift analysis of several representatives of the labdane diterpene family of natural products is presented. The shift assignment is based on the prior shift designation of some synthetic trans-decalin derivatives.     

Temperature dependence of the exciton and magnon-phonon sidebands in RbMnF3 in the 5500Å region

Absorption spectra of RbMnF₃ in the 5500Å region were investigated in the temperature interval 4.2–77°K. Similar temperature dependence was observed for the exciton-magnon and the magnon-phonon sidebands. The position of the exciton lines does not vary as the temperature is increased.     

High-resolution infrared spectrum of the ν1 + ν3 band of ozone

The ν₁ + ν₃ band of ozone (O₃) near 2110 cm^?1 has been measured and analyzed using a Watson-type Hamiltonian including all seven sextic centrifugal distortion terms. Two weak perturbations have been found between K = n of ν₁ + ν₃ and K = n + 3 of 2ν₃. Those perturbations locate the band center for 2ν₃ at about 2058 cm^?1. Aside from those perturbations the interactions of ν₁ + ν₃ with 2ν₁ and 2ν₃ have not been taken into account in the analysis. Effective band constants and an atlas listing line wavenumbers and assignments are given.     

Infrared tunable diode laser spectra of lithium fluoride at high temperatures

At temperatures up to 1300 K the high resolution spectrum has been measured for the 1-0 through 7-6 vibrational transitions of ⁷LiF and the 1-0 through 8-7 vibrational transitions of ⁶LiF. These infrared ro-vibrational measurements have been combined with microwave measurements taken from the literature to obtain a set of ten Dunham potential constants that reproduce all the measurements for both isotopic species to within their experimental uncertainty. The band center for the v = 1-0 transition is 894.34104±0.00020 cm^?1 for ⁷LiF and 946.12074±0.00024 cm^?1 for ⁶LiF.     

Stereospecific synthesis of dinosterol

Using a Claisen ortho-ester rearrangement, the biogenetically important marine sterol dinosterol and its C-24 epimer were synthesized stereospecifically by a sequence which is also attractive for selective isotope labelling in the side chain.     

Stereoelectronic effects on metallation of 1,3-dioxanes

Metallation of the acetal (H-2) proton in 1,3-dioxolanes, 1,3-dioxanes and open chain acetals is possible only if the proton can occupy an “equatorial-like” conformation.