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pro vyhledávání: '"39"'
Publikováno v:
ChemInform. 24
Procedures are described for the attempted conversion of the pyrrolidine (2) into a bicyclic system that would ultimately lead to retronecine (3). The only molecule to be isolated from these attempts was the epimeric ketone (6), and AM1 and MM2 calcu
Autor:
Barry B. Snider, Zhongping Shi
Publikováno v:
ChemInform. 25
The methyl ester of the pentacyclic nucleus of ptilomycalin A (9) has been prepared by an efficient, convergent, biogenetic, 14-step route. The key steps involve the conversion of acyclic bis enone 39 to 9 in four steps. Michael addition of O-methyli
Autor:
Iyassu K. Sebhat, Philip Magnus
Publikováno v:
ChemInform. 30
o-Vanillin 21 was converted into 24 following literature procedures. Treatment of 24 withn-BuLi/THF followed by addition of 25 gave 26 . Dehydration (POCl 3 /pyridine/DBU), hydrogenation and hydrolysis of 26 gave the ketone 29 . Chirality was introdu
Publikováno v:
ChemInform. 28
Methylation of methyl 4-phenylpentanoate 25 gives the diastereoisomers methyl (2RS,4SR )-2-methyl-4-phenylpentanoate 26 and methyl (2RS,4RS)- 2-methyl-4-phenylpentanoate 27 in a ratio of 44∶56. The aldehydes 3-dimethyl(phenyl)silylbutanal 28, 3-dim
Autor:
Rüdiger Ozegowski, Helmut Dorn
Publikováno v:
ChemInform. 29
1-Substituted 3-hydroxy-1H-pyrazoles 1 react with chloroform, NaOH, and aceton resp. butan-2-one O-regiospecifically to yield 2-methyl-2-[(1H-pyrazol-3-yl)oxy]-propanoic resp. -butanoic acids 14via a dichlorocarbene (12)–dichlorooxirane (9) pathway
Publikováno v:
ChemInform. 29
1,4-Anhydro-3-O-benzyl-2,5-dideoxy-4a-carba-DL- erythro -hex-1-enitol-uronic acid ( 5 ) was transformed by chain degradation under suitable protection and reaction with m -CPBA into 5-O-acetyl-1,2-anhydro-4a-carba-α-DL-xylofuranose ( 37 ). Replaceme
Publikováno v:
ChemInform. 30
The intramolecular Lewis acid mediated cyclization of γ-alkoxyallylstannanes 1, 2, and 14, bearing a hydrazone group at the terminus of the carbon chain, afforded exclusively the corresponding trans β-amino cyclic ethers 3a, 4a, and 15, respectivel
Autor:
Takayuki Yakura
Publikováno v:
ChemInform. 32
This review summarizes novel stereoselective syntheses of 3,4-cis- and 3,4-trans-3-alkyl-4-silyloxycyclopentanones using a dirhodium(II)-catalyzed intramolecular C-H insertion reaction as a key reaction. Treatment of diazoketoesters (20a-e) with 1 mo
Autor:
Kathleen M. Bertini Gross, Peter Beak
Publikováno v:
ChemInform. 32
A series of selected bicyclic carbamates in which the range of accessible angles and distances between the carbonyl group and the proton removed in an alpha-lithiation reaction are structurally defined have been investigated. Oxazolidinones 7-10 unde
Publikováno v:
ChemInform. 33
Rhodium carboxylate catalyzed aromatic addition reactions of a range of diazoketones bearing methoxy-substituted aryl rings have been explored. While the existence of norcaradiene−cycloheptatriene equilibria in related compounds is well established