Remote asymmetric induction in an intramolecular ionic Diels-Alder reaction: application to the total synthesis of (+)-dihydrocompactin

The total synthesis of (+)-dihydrocompactin via an intramolecular ionic Diels-Alder reaction that proceeds with remote stereocontrol is described. This reaction proceeds by an intermediate vinyl-oxocarbenium ion (6), the conformational constraints of which lead to the observed asymmetric induction. The sense of asymmetric induction appears contrasteric and is explained by the proposed reactive conformation shown in Figure 1.     

Fast emulsion droplet sizing using NMR self-diffusion measurements

Emulsion droplet sizing using pulsed field gradient (PFG) nuclear magnetic resonance (NMR) is a well-established technique. Traditionally these measurements require total acquisition times of typically 5-20 min per sample, which severely limits our ability to use this method to study dynamic processes. Here we present the application and verification of an NMR pulse sequence, Difftrain, which enables emulsion droplet size distributions to be measured in 3-10 s. We have previously introduced applications of Difftrain (C. Buckley, K.G. Hollingsworth, A.J. Sederman, D.J. Holland, M.L. Johns, L.F. Gladden, J. Magn. Reson. 161 (2003) 112-117), including the droplet sizing of a single unimodal emulsion sample. In this paper, several model emulsions containing different oils are measured and the results compared directly with sizing provided by laser scattering. In this manner, the Difftrain method is verified and its possibilities and limitations are explored. Guidelines are proposed for the range of droplet sizes for which accurate results can be produced. The Difftrain technique opens up the possibility of studying non-equilibrium emulsions; a study of the in situ emulsification of a 21% v/v water-in-silicone oil emulsion is presented.     

High-resolution Fourier transform spectroscopy of the ν2 and ν3 fundamentals of nitrosyl fluoride,FNO

The ν₂ and ν₃ fundamentals of FNO have been recorded with a Fourier transform spectrophotometer at an apodized resolution of approximately 0.004 cm^?1. The Fourier infrared data have been analyzed together with previous microwave data to yield improved molecular parameters for the (000) and (010) vibrational states and the first set of constants for the (001) state. The main results (in cm^?1) are

     

154.

Abelian and non-Abelian bosonization: The operator solution of the WZW sigma model     

do Amaral RL  Stephany Ruiz JE 《Physical review D: Particles and fields》1991,43(6):1943-1948

     

155.

Mass spectra of indazolones and pyrazolones—I: Indazolones     

J. M. Desmarchelier  R. B. Johns 《Journal of mass spectrometry : JMS》1969,2(1):37-47

The mass spectral fragmentations of 3-indazolone (I), 1-acetyl-3-acetoxyindazol (II), 1,2-diacetyl-3-indazolone (III), 1-methyl-3-indazolone (IV), 2-methyl-3-indazolone (V), 2-methyl-3-indazolone-N-d-1 (VI), 3-methoxy-indazole (VII), 1-ethyl-3-indazolone (VIII), 1-carbethoxy-3-indazolone (IX), 1-carbethoxy-2-methyl-3-indazolone (X), 2′-carboxyethyl-3-indazolone (XI), 1-oxo-2,3-dihydropyrazolo-(1,2-α)-3-indazolone (XII) and 1-ethyl-3-indazolone-N-d-2 (XIII) are reported. The loss of an ·N₂R radical from the parent radical ion in indazolone and the alkyl indazolones occurs more readily than the loss of a formyl radical, and no loss of HCN is observed from the parent radical ion. Mass spectral data can be used to distinguish between N-methyl and O-methyl derivatives of 3-indazolone.     

156.

Bis(1‐ferrocenylbutane‐1,3‐dionato‐κ2O,O′)copper(II) and bis­(1,3‐diferrocenylpropane‐1,3‐dionato‐κ2O,O′)­copper(II)     

Peter D.W. Boyd  Paul M. Johns  Clifton E.F. Rickard 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):m590-m593

The title compounds, [CuFe₂(C₅H₅)₂(C₉H₈O₂)₂], (I), and [CuFe₄(C₅H₅)₄(C₁₃H₉O₂)₂], (II), are four‐coordinate square‐planar copper(II) complexes with two bidentate 1‐ferrocenylbutane‐1,3‐dionate or 1,3‐diferrocenylpropane‐1,3‐dionate ligands, respectively. The copper ion in (I) lies on an inversion centre, with one‐half of the mol­ecule in the asymmetric unit, while in (II), there are two independent half mol­ecules in the asymmetric unit, with the copper ions also situated on inversion centres. The ferrocene substituents in (I) are in an anti arrangement. The mol­ecules assemble in the crystal structure in layers with ferrocene groups at the surface. The pairs of ferrocene substituents on each ligand in complex (II) are syn and these adopt an anti arrangement with respect to the pair on the other diketonate ligand. As found in (I), complexes assemble in a layered structure with ferrocene‐coated surfaces.     

157.

Stereoselective synthesis of C5-C20 and C21-C34 subunits of the core structure of the aplyronines. Applications of enantioselective additions of chiral allenylindium reagents to chiral aldehydes     

Marshall JA  Johns BA 《The Journal of organic chemistry》2000,65(5):1501-1510

The stereoselective synthesis of a C5-C20 and a C21-C34 subunit of the aplyronine family of polyketide marine macrolides has been achieved. These subunits contain all 15 stereocenters of the core structure. Six of the 15 stereocenters were introduced through enantioselective and diastereoselective additions of chiral allenylindium reagents to alpha-methyl-beta-oxygenated propionaldehydes. The products of these additions were further transformed by reactions involving the terminal alkynyl substituent produced in the addition reactions. Unlike previous applications of this methodology, the present synthesis employs Pd(0)-catalyzed transmetalations of chiral allenylpalladium intermediates to generate the chiral allenylindium reagents in situ.     

158.

High-resolution far-infrared spectroscopy of C-13 methanol     

I. Mukhopadhyay  R. M. Lees  J. W. C. Johns 《International Journal of Infrared and Millimeter Waves》1988,9(12):1119-1140

The high-resolution far-infrared (FIR) Fourier transform spectrum of¹³CH₃OH has been studied from 25–350 cm^–1, andb-type^rR-branches in the torsional ground state have been assigned. The branches have been fitted to phenomeno-logical expansion parameters, which reproduce the branch frequencies generally to well within ±0.001 cm^–1. An interesting and relatively novel K=4 perturbation, localized to levels around J=18, has been observed between (nK)=(019) and (125) states.     

159.

Displacement propagators of brine flowing within different types of sedimentary rock     

Verganelakis DA  Crawshaw J  Johns ML  Mantle MD  Scheven U  Sederman AJ  Gladden LF 《Magnetic resonance imaging》2005,23(2):349-351

This paper explores the correlation between different microstructural characteristics of porous sedimentary rocks and the flow properties of a Newtonian infiltrating fluid. Preliminary results of displacement propagator measurements of brine solution flowing through two types of sedimentary rock cores are reported. The two types of rocks, Bentheimer and Portland, are characterized by different porosities, pore-size distributions and permeabilities. Propagators have been measured for brine flow rates of 1 and 5 ml/min. Significant differences are seen between the propagators recorded for the two rocks, and these are related to the spatial distribution of porosity within these porous media.     

160.

High-resolution laser Stark and Fourier transform spectroscopy of the ν₂ fundamental band of HFCO     

M. Wong  J.W.C. Johns  A.R.W. McKellar 《Journal of Molecular Spectroscopy》1982,94(1):79-94

The ν₂ (CO stretch) fundamental band of formyl fluoride (HFCO) was studied in the region 1800 to 1910 cm^?1 using the two techniques of intracavity CO laser Stark spectroscopy at sub-Doppler resolution and Fourier transform spectroscopy at Doppler-limited resolution. Accurate values of the molecular parameters of the ground and excited (v₂ = 1) vibrational states were obtained from a combined fit of the ν₂ band data and available microwave data. The results include precise determinations of the electric dipole moment components (μ_a and μ_b) of HFCO in the ground and excited states.     

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	Ground state	$\text{ν}{}_2$	$\text{ν}{}_3$
A	3.1751882 (17)	3.1861249 (12)	3.1958722 (15)
B	0.39508266 (12)	0.39407878 (14)	0.39211484 (14)
C	0.35051504 (11)	0.34899779 (16)	0.34747411 (14)
$\text{ν}{}_0$	0	765.3551 (4)	519.5980 (4)

Mass spectra of indazolones and pyrazolones—I: Indazolones

The mass spectral fragmentations of 3-indazolone (I), 1-acetyl-3-acetoxyindazol (II), 1,2-diacetyl-3-indazolone (III), 1-methyl-3-indazolone (IV), 2-methyl-3-indazolone (V), 2-methyl-3-indazolone-N-d-1 (VI), 3-methoxy-indazole (VII), 1-ethyl-3-indazolone (VIII), 1-carbethoxy-3-indazolone (IX), 1-carbethoxy-2-methyl-3-indazolone (X), 2′-carboxyethyl-3-indazolone (XI), 1-oxo-2,3-dihydropyrazolo-(1,2-α)-3-indazolone (XII) and 1-ethyl-3-indazolone-N-d-2 (XIII) are reported. The loss of an ·N₂R radical from the parent radical ion in indazolone and the alkyl indazolones occurs more readily than the loss of a formyl radical, and no loss of HCN is observed from the parent radical ion. Mass spectral data can be used to distinguish between N-methyl and O-methyl derivatives of 3-indazolone.     

Bis(1‐ferrocenylbutane‐1,3‐dionato‐κ2O,O′)copper(II) and bis­(1,3‐diferrocenylpropane‐1,3‐dionato‐κ2O,O′)­copper(II)

The title compounds, [CuFe₂(C₅H₅)₂(C₉H₈O₂)₂], (I), and [CuFe₄(C₅H₅)₄(C₁₃H₉O₂)₂], (II), are four‐coordinate square‐planar copper(II) complexes with two bidentate 1‐ferrocenylbutane‐1,3‐dionate or 1,3‐diferrocenylpropane‐1,3‐dionate ligands, respectively. The copper ion in (I) lies on an inversion centre, with one‐half of the mol­ecule in the asymmetric unit, while in (II), there are two independent half mol­ecules in the asymmetric unit, with the copper ions also situated on inversion centres. The ferrocene substituents in (I) are in an anti arrangement. The mol­ecules assemble in the crystal structure in layers with ferrocene groups at the surface. The pairs of ferrocene substituents on each ligand in complex (II) are syn and these adopt an anti arrangement with respect to the pair on the other diketonate ligand. As found in (I), complexes assemble in a layered structure with ferrocene‐coated surfaces.     

Stereoselective synthesis of C5-C20 and C21-C34 subunits of the core structure of the aplyronines. Applications of enantioselective additions of chiral allenylindium reagents to chiral aldehydes

The stereoselective synthesis of a C5-C20 and a C21-C34 subunit of the aplyronine family of polyketide marine macrolides has been achieved. These subunits contain all 15 stereocenters of the core structure. Six of the 15 stereocenters were introduced through enantioselective and diastereoselective additions of chiral allenylindium reagents to alpha-methyl-beta-oxygenated propionaldehydes. The products of these additions were further transformed by reactions involving the terminal alkynyl substituent produced in the addition reactions. Unlike previous applications of this methodology, the present synthesis employs Pd(0)-catalyzed transmetalations of chiral allenylpalladium intermediates to generate the chiral allenylindium reagents in situ.     

High-resolution far-infrared spectroscopy of C-13 methanol

The high-resolution far-infrared (FIR) Fourier transform spectrum of¹³CH₃OH has been studied from 25–350 cm^–1, andb-type^rR-branches in the torsional ground state have been assigned. The branches have been fitted to phenomeno-logical expansion parameters, which reproduce the branch frequencies generally to well within ±0.001 cm^–1. An interesting and relatively novel K=4 perturbation, localized to levels around J=18, has been observed between (nK)=(019) and (125) states.     

Displacement propagators of brine flowing within different types of sedimentary rock

This paper explores the correlation between different microstructural characteristics of porous sedimentary rocks and the flow properties of a Newtonian infiltrating fluid. Preliminary results of displacement propagator measurements of brine solution flowing through two types of sedimentary rock cores are reported. The two types of rocks, Bentheimer and Portland, are characterized by different porosities, pore-size distributions and permeabilities. Propagators have been measured for brine flow rates of 1 and 5 ml/min. Significant differences are seen between the propagators recorded for the two rocks, and these are related to the spatial distribution of porosity within these porous media.     

High-resolution laser Stark and Fourier transform spectroscopy of the ν2 fundamental band of HFCO

The ν₂ (CO stretch) fundamental band of formyl fluoride (HFCO) was studied in the region 1800 to 1910 cm^?1 using the two techniques of intracavity CO laser Stark spectroscopy at sub-Doppler resolution and Fourier transform spectroscopy at Doppler-limited resolution. Accurate values of the molecular parameters of the ground and excited (v₂ = 1) vibrational states were obtained from a combined fit of the ν₂ band data and available microwave data. The results include precise determinations of the electric dipole moment components (μ_a and μ_b) of HFCO in the ground and excited states.