Results 201 to 210 of about 46,060 (245)
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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 ...
Samadi, M. +3 more
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, 2009 Synthesis of the C29−C44 Portion of Spongistatin 1 (Altohyrtin A)
The 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.
G A, Wallace, R W, Scott, C H, Heathcock
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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.
G R, Ott, C H, Heathcock
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Low-temperature behavior of the elastic constant C44 in CexLa1−xB6
Physica B: Condensed Matter, 2002Abstract We have made the ultrasonic experiments to examine the low-temperature elastic properties in the Kondo compound Ce x La 1− x B 6 for x =0.70, 0.65 and 0.60. The transverse C 44 mode in x =0.70 and 0.65 shows steep decrease as much as 25% around the transition point into the ordered phase IV.
Yuichi Nemoto +5 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.
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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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C44. Secure cooperative blindly-optimized compressive spectrum sensing for cognitive radio
2012 29th National Radio Science Conference (NRSC), 2012In this paper, we propose a reduced complexity secure cooperative cognitive radio spectrum sensing algorithm for wideband systems. The proposed scheme aims to reduce the receiver hardware complexity by minimizing the required sampling rates. The proposed scheme is immune to spectrum sensing data falsification attacks.
Mohammed Farrag +2 more
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The Role of Softening in Elastic Constant c44 in Martensitic Transformation
Scripta Materialia, 1998In the present paper, the authors show that the puzzling monoclinic distortion in TiNi martensite B19{prime} has a simple origin. It is due to the softening of {l_brace}001{r_brace} shear modulus c{sub 44} (which is also the {l_brace}001{r_brace} shear modulus by definition), which leads to a correlation of this shear mode with that of basal shear ...
Xiaobing Ren, Kazuhiro Otsuka
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