Total Syntheses of Seven Stemoamide-Type Stemona Alkaloids

2022 ◽  
Author(s):  
Tao Shi ◽  
Fei Cao ◽  
Jin hong Chen ◽  
Xiao-Dong Wang ◽  
Gaofeng Yin ◽  
...  
Keyword(s):  
Total Syntheses ◽  
Transannular Cyclization ◽  
Cascade Cyclization ◽  
The Common ◽  
Stemona Alkaloids

Six Stemona alkaloids were synthesized racemically by using stemoamide, obtained via cascade cyclization or our reported transannular cyclization of parvistemoamide, as the common intermediate. Thioamides facilitated the separation of isosaxorumamide...

Formal Total Syntheses of Crocacin A-D

2005 ◽  
Vol 70 (10) ◽  
pp. 1696-1708 ◽  
Author(s):  
Magnus Besev ◽  
Christof Brehm ◽  
Alois Fürstner
Keyword(s):  
Natural Products ◽  
Aldol Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Total Syntheses ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
The Common ◽  
Selective Addition

A concise route to the common polyketide fragment5of crocacin A-D (1-4) is presented which has previously been converted into all members of this fungicidal and cytotoxic family of dipeptidic natural products by various means. Our synthesis features asyn-selective titanium aldol reaction controlled by a valinol-derived auxiliary, a zinc-mediated, palladium-catalyzedanti-selective addition of propargyl mesylate10to the chiral aldehyde9, as well as a comparison of palladium-catalyzed Stille and Suzuki cross-coupling reactions for the formation of the diene moiety of the target.

scholarly journals Evolution of the Total Syntheses of Batzellasides the First Marine Piperidine Iminosugar

2013 ◽  
Vol 8 (7) ◽  
pp. 1934578X1300800
Author(s):  
Tetsuya Sengoku ◽  
Jolanta Wierzejska ◽  
Masaki Takahashi ◽  
Hidemi Yoda
Keyword(s):  
Total Synthesis ◽  
First Generation ◽  
Ring System ◽  
Piperidine Ring ◽  
Total Syntheses ◽  
Asymmetric Dihydroxylation ◽  
Biological Studies ◽  
The Common ◽  
Absolute Stereochemistry

Batzellasides A-C are C-alkylated piperidine iminosugars isolated from a sponge Batzella sp. The first total synthesis of (+)-batzellaside B was achieved by employing a chiral pool approach starting from L-arabinose for the construction of a piperidine ring system. Subsequently a practical second-generation synthesis was developed by utilizing a Sharpless asymmetric dihydroxylation for the preparation of the common piperidine intermediate elaborated in the first-generation synthesis. The overall yield of batzellaside B was improved to 3.3% by introducing the exocyclic C8 stereocenter via facial selective hydride addition to a linear ketone. These syntheses allowed for the determination of the absolute stereochemistry of this natural product as well as for providing precious samples which would pave the way for further biological studies.

Total syntheses of (−)-vallesamidine and related Aspidosperma and Hunteria type indole alkaloids from the common intermediate

Tetrahedron ◽  
2004 ◽  
Vol 60 (14) ◽  
pp. 3273-3282 ◽  
Author(s):  
Hideo Tanino ◽  
Kazuhisa Fukuishi ◽  
Mina Ushiyama ◽  
Kunisuke Okada
Keyword(s):  
Indole Alkaloids ◽  
Total Syntheses ◽  
The Common

Nucleosides. 118. Total syntheses of pentopyranine B and D. Cytosine nucleosides elaborated by Streptomyces griseochromogenes

1981 ◽  
Vol 59 (2) ◽  
pp. 468-472 ◽  
Author(s):  
Kyoichi A. Watanabe ◽  
Akira Matsuda ◽  
Tsuneo Itoh
Keyword(s):  
Natural Products ◽  
Total Syntheses ◽  
The Common

Pentopyranine B and D, pentopyranosylcytosine nucleosides elaborated by Streptomyces griseochromogenes, have been synthesized from the common intermediate, methyl 4-O-benzoyl-3-deoxy-3-iodo-β-D-xylopyranoside (1). The synthetic products, l-(2,3-dideoxy-β-D-glyceropentopyranosyl)cytosine (18) and l-(3-deoxy-β-D-erythropentopyranosyl)cytosine (7) were identical with the natural products, pentopyranine B and D, respectively.

Catalogue reduction techniques

1978 ◽  
Vol 48 ◽  
pp. 389-390 ◽  
Author(s):  
Chr. de Vegt
Keyword(s):  
Adjustment Process ◽  
Proper Motions ◽  
Measuring Process ◽  
Aerial Photogrammetry ◽  
Reduction Techniques ◽  
Observational Technique ◽  
The Common ◽  
Astrometric Data

AbstractReduction techniques as applied to astrometric data material tend to split up traditionally into at least two different classes according to the observational technique used, namely transit circle observations and photographic observations. Although it is not realized fully in practice at present, the application of a blockadjustment technique for all kind of catalogue reductions is suggested. The term blockadjustment shall denote in this context the common adjustment of the principal unknowns which are the positions, proper motions and certain reduction parameters modelling the systematic properties of the observational process. Especially for old epoch catalogue data we frequently meet the situation that no independent detailed information on the telescope properties and other instrumental parameters, describing for example the measuring process, is available from special calibration observations or measurements; therefore the adjustment process should be highly self-calibrating, that means: all necessary information has to be extracted from the catalogue data themselves. Successful applications of this concept have been made already in the field of aerial photogrammetry.

Renilla Bioluminescence: A Morphologic Approach to the Location of Photocytes

1974 ◽  
Vol 32 ◽  
pp. 208-209
Author(s):  
Ben O. Spurlock ◽  
Milton J. Cormier
Keyword(s):  
Excited State ◽  
Ground State ◽  
Molecular Basis ◽  
Light Emission ◽  
Chemical Basis ◽  
Electronic Excited State ◽  
Colonial Form ◽  
The Common ◽  
Eighteenth And Nineteenth Centuries ◽  
Catalyzed Oxidation

The phenomenon of bioluminescence has fascinated layman and scientist alike for many centuries. During the eighteenth and nineteenth centuries a number of observations were reported on the physiology of bioluminescence in Renilla, the common sea pansy. More recently biochemists have directed their attention to the molecular basis of luminosity in this colonial form. These studies have centered primarily on defining the chemical basis for bioluminescence and its control. It is now established that bioluminescence in Renilla arises due to the luciferase-catalyzed oxidation of luciferin. This results in the creation of a product (oxyluciferin) in an electronic excited state. The transition of oxyluciferin from its excited state to the ground state leads to light emission.

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