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Stereospecific and Stereoselective...

Figure presented A divergent short synthesis of four diastereomers of pachastrissamine was achieved. Natural pachastrissamine was synthesized through bis-tosylation of the common intermediate and cyclization. 2-epi- Pachastrissamine was obtained by monotosylation and spontaneous cyclization of d-ribo-phytosphingosine derivative. By use of regio- and stereospecific ring-opening reaction of the orthoester assisted by a Boc group as a key step, 3-epi- and 2,3-epi-pachastrissamines were synthesized. The three stereogenic centers of all the diastereomers were constructed by using Garners aldehyde as the sole chiral source.

Stereospecific and Stereoselective Oxidative Coupling of a Chiral Tetrahydronaphthol

An early approach to non-racemic alkylidene-cyclopropanes utilized the stereospecific, formal [1,3] carbon shift of Fiest’s ester, a methylenecyclopropane which is readily available in enantiomerically pure form. However, the preparative utility of such rearrangements of methylenecyclopropanes to alkylidenecyclopropanes is typically limited by the need for pyrolytic conditions. Studies by Gardner, Creary and Nakamura have shown that aryl or alkoxy, substituted methylenecyclopropanes rearrange to alkylidenecyclopropanes under mild conditions. However, the stereospecificity of the rearrangements of methylenecyclopropanes with stabilizing substitutents had not been tested. Moreover, there was no method to access enantiomerically enriched methylenecyclopropanes with substituents that facilitate the [1,3]-carbon shift reaction.

Stereospecific and Stereoselective Reactions

stereoselective and stereospecific synthesis - authorstream presentation ..

AB - (±)-Clavukerin A and (±)-isoclavukerin A were synthesized stereoselectively utilizing stereospecific palladium-catalyzed reductive cleavage of alkenylcyclopropanes with formic acid.

N2 - Figure presented A divergent short synthesis of four diastereomers of pachastrissamine was achieved. Natural pachastrissamine was synthesized through bis-tosylation of the common intermediate and cyclization. 2-epi- Pachastrissamine was obtained by monotosylation and spontaneous cyclization of d-ribo-phytosphingosine derivative. By use of regio- and stereospecific ring-opening reaction of the orthoester assisted by a Boc group as a key step, 3-epi- and 2,3-epi-pachastrissamines were synthesized. The three stereogenic centers of all the diastereomers were constructed by using Garners aldehyde as the sole chiral source.

Direct Stereospecific Synthesis of Unprotected N-H and …

stereoselective & stereospecific synthesis: stereoselective & stereospecific synthesis 1.

Facile Stereoselective Synthesis of E and Z Substituted Cinnamates Stereospecific Dehydration Reaction With 1 Ethyl 3 3 Dimethylaminopropyl Carbodiimi will be available on

The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center.

the term stereospecific reaction' is commonly misused to mean 'highly stereoselective reaction'
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Stereoselective and stereospecific synthesis essay

N2 - A synthesis of the E-isomer of the proposed structure of the novel tripeptide, lucentamycin A, was performed in an attempt to define the correct stereochemistry of this natural product. The synthetic route developed employs a stereoselective Rh-catalyzed reductive cyclization process to generate the key pyrrolidine residue in the target and a stereospecific inversion of the Z-olefin geometry to form desired E-isomer. Subsequent amide coupling reactions afforded the desired E-isomer of putative lucentamycin A. A comparison of the NMR data of synthetic E-1a with that of the naturally occurring lucentamycin A demonstrated that they are not identical substances and the E-1a was found to display no anti-proliferative activity on the colon cancer cell line HCT-116 in contrast to natural lucentamycin A.

SCI - Stereospecific and Catalytic Synthesis

AB - Figure presented A divergent short synthesis of four diastereomers of pachastrissamine was achieved. Natural pachastrissamine was synthesized through bis-tosylation of the common intermediate and cyclization. 2-epi- Pachastrissamine was obtained by monotosylation and spontaneous cyclization of d-ribo-phytosphingosine derivative. By use of regio- and stereospecific ring-opening reaction of the orthoester assisted by a Boc group as a key step, 3-epi- and 2,3-epi-pachastrissamines were synthesized. The three stereogenic centers of all the diastereomers were constructed by using Garners aldehyde as the sole chiral source.

11.12.2013 · Stereospecific and Catalytic Synthesis

AB - A synthesis of the E-isomer of the proposed structure of the novel tripeptide, lucentamycin A, was performed in an attempt to define the correct stereochemistry of this natural product. The synthetic route developed employs a stereoselective Rh-catalyzed reductive cyclization process to generate the key pyrrolidine residue in the target and a stereospecific inversion of the Z-olefin geometry to form desired E-isomer. Subsequent amide coupling reactions afforded the desired E-isomer of putative lucentamycin A. A comparison of the NMR data of synthetic E-1a with that of the naturally occurring lucentamycin A demonstrated that they are not identical substances and the E-1a was found to display no anti-proliferative activity on the colon cancer cell line HCT-116 in contrast to natural lucentamycin A.

substitution can be stereoselective in ..

N2 - (±)-Clavukerin A and (±)-isoclavukerin A were synthesized stereoselectively utilizing stereospecific palladium-catalyzed reductive cleavage of alkenylcyclopropanes with formic acid.

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