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Synthetic studies on spongistatins: synthesis of the C29–C44 fragment
Tetrahedron Letters, 2000Abstract A convergent synthesis of the C29–C44 fragment, the common subunit of the spongipyran macrolides is described. The key step of the synthesis is the C -glycosidation reaction which is based on coupling of the lithiated F-ring sulfone with the E-ring aldehyde, and subsequent reductive desulfonylation to afford the E–F bis (pyran) with high ...
Michele Guyot +2 more
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Synthetic Strategy toward the C44–C65 Fragment of Mirabalin
Organic Letters, 2014A convergent and flexible stereoselective synthesis of one isomer of the C44-C65 fragment of mirabalin is described. The key steps include organocatalytic aldolization, ruthenium-catalyzed asymmetric hydrogenation, amide formation, Marshall stereoselective allenylation, and the Nozaki-Hiyama-Kishi reaction.
Sébastien Prevost +2 more
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Shear Elastic Constant C44 and Phase Transformation of KCl
Nature, 1973THE shear elastic constant C44 for KCl, KF and the rubidium halides is of special interest because it decreases with pressure. Born1 and Misra2 pointed out that a vanishing shear elastic constant is a sufficient condition for a phase transformation.
Wang Chi-Yuen
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Synthesis of the C29−C44 Portion of Spongistatin 1 (Altohyrtin A)
Journal of Organic Chemistry, 2000Two synthetic approaches to the C29-C44 portion of spongistatin 1 (altohyrtin A) have been developed. The key step of the first approach relies on the Claisen rearrangement of glucal 18 to provide ester 20a. This intermediate was advanced to silyl enol ether 30, which was coupled under Mukaiyama aldol conditions with aldehyde 3.
Clayton H Heathcock, Robert W Scott
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A Method for Constructing the C44−C51 Side Chain of Altohyrtin C
Organic Letters, 1999[formula: see text] A method to construct the C44-C51 side chain of altohyrtin C has been developed and applied to a model aldehyde derived from D-glucose. The approach relies on a Wittig reaction to couple the side chain to an aldehyde and utilizes an allylic diazene rearrangement to place the C45 double bond in the correct position.
Clayton H Heathcock
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On the softening of the elastic constant, C44, in graphite
Solid State Communications, 1979Abstract The shear mode associated with the interplanar elastic parameter C 44 of graphite is anomalously soft in the low frequency region. An analysis of dislocation dynamics has been made and several experiments are described which explore the temperature, pressure and magnetic field dependence of C 44 .
J.B. Ayasse +4 more
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Stereoselective synthesis of the C33–C44 fragment of palau’amide
Tetrahedron Letters, 2008Abstract An efficient stereoselective synthesis of the C33–C44 fragment of palau’amide is described using a Sharpless asymmetric epoxidation, a regioselective nucleophilic ring opening of the epoxide, a Grignard reaction and a Luche stereoselective reduction of a keto compound as the key steps.
Debendra K. Mohapatra, Sabita Nayak
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Relative Energetics of C44 Fullerene Isomers
1992We have carried out an exhaustive search of the energetics of all 87 isomers of the fullerene C44 using an empirical potential function. We find no single structural isomer with exceptional stability, suggesting that the enhanced abundance of this cluster observed in some studies may be due to a mixture of different molecules.
M. Lyons +6 more
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