Intramolecular cyclization of O-alkyl-N-(3-phenylpropenoyl)thiocarbamates catalyzed by boron trifluoride

1990 ◽  
Vol 55 (3) ◽  
pp. 710-717 ◽  
Author(s):  
Milan Dzurilla ◽  
Peter Kutschy ◽  
Dušan Koščík ◽  
Štefan Toma
Keyword(s):  
Methyl Ester ◽  
Intramolecular Cyclization ◽  
Alkyl Group ◽  
Boron Trifluoride ◽  
Intramolecular Rearrangement

2-Alkoxy-6-phenyl-5,6-dihydro-4H-1,3-thiazin-4-ones, 6-phenyl-1,3-perhydrothiazine-2,4-dione and S-methyl N-(3-phenylpropenoyl)thiocarbamate are the products of intramolecular rearrangement of O-alkyl N-(3-phenylpropenoyl)thiocarbamates catalyzed by boron trifluoride; their formation depends on the nature of the alkyl group. The rearrangement was shown to proceed intermolecularly by investigating the reaction of O-methyl N-(3-phenylpropenoyl)thiocarbamate to an S-methyl ester by the method of a crossover experiment.

Rearrangements of ethylene oxide derivatives. Stereoselectivity of the prochiral C1 hydrogens in the boron trifluoride catalysed rearrangement of 1,2-epoxyoctane

1977 ◽  
Vol 30 (5) ◽  
pp. 1137 ◽  
Author(s):  
JM Coxon ◽  
C Lim
Keyword(s):  
Ethylene Oxide ◽  
Alkyl Group ◽  
Boron Trifluoride

The boron trifluoride catalysed rearrangement of 1,2-epoxyoctane to give octanal proceeds by selective (c. 1.4 : 1) migration of the prochiral hydrogen trans to the alkyl group.

Copper-Catalyzed Synthesis of Substituted 4-Acylpyrazole Derivatives through a Cascade Transformation from N-Propargylic Sulfonylhydrazones and Diaryliodonium Salts

Synlett ◽  
2018 ◽  
Vol 29 (17) ◽  
pp. 2283-2287 ◽  
Author(s):  
Yi-Hui Chen ◽  
Ren-Hao Li ◽  
Xin-Yang Fan ◽  
Zi-Lin Hu ◽  
Zhi-Kai Liu ◽  
...  
Keyword(s):  
Intramolecular Cyclization ◽  
Aerobic Oxidation ◽  
Intramolecular Rearrangement ◽  
Pyrazole Derivatives ◽  
Diaryliodonium Salts

A concise strategy for the synthesis of substituted 4-acylpyrazole derivatives from N-propargylic sulfonylhydrazones and diaryliodonium salts has been developed. The pyrazole derivatives are formed through a five-step cascade sequence that includes intramolecular cyclization, hydroxylation, elimination, copper-catalyzed aerobic oxidation, and intramolecular rearrangement.

Synthesis of optically active l-acyl-2-O-alkyl-sn-glycero-3-phosphocholine via 1-O-benzyl-sn-glycerol 3-arenesulfonate

1990 ◽  
Vol 68 (1) ◽  
pp. 360-365 ◽  
Author(s):  
Shaukat Ali ◽  
Robert Bittman
Keyword(s):  
Benzyl Alcohol ◽  
Alkyl Group ◽  
Boron Trifluoride ◽  
Enantiomeric Excess ◽  
Boron Trifluoride Etherate ◽  
Optically Active ◽  
Epoxide Ring ◽  
Phospholipid Synthesis ◽  
Tert Butyl ◽  
Very High

A stereocontrolled route to 1-palmitoyl-2-O-hexadecyl-sn-glycero-3-phosphocholine from (R)-glycidyl tosylate is described. This method gives very high enantioselectivity (93–96% enantiomeric excess) and can be used to prepare 3-acyl-2-O-alkyl-sn-glycero-1-phosphocholines from (S)-glycidyl tosylate. The key step is the preparation of 1-O-benzyl-sn-glycerol 3-tosylate by the boron trifluoride etherate catalyzed regio- and stereo-specific opening of the epoxide ring with excess benzyl alcohol. The alkyl group is introduced using alkyl trifluoromethanesulfonate in the presence of excess 2,6-di-tert-butyl-4-methylpyridine. Debenzylation gives 2-O-alkyl-sn-glycerol 3-arenesulfonate, which is acylated and then converted into the phosphocholine. The use of chiral glycidyl derivatives as starting materials for the synthesis of glycerophospholipids is discussed.Key words: acylalkylglycerophospholipids, phospholipid synthesis, glycidyl derivatives in phospholipid synthesis, epoxides as precursors of phospholipids.

STEROIDS AND RELATED PRODUCTS: XIX. THE SYNTHESIS OF 3,9,12,20-TETRAOXYGENATED 9,12-seco STEROIDS. PART III. 11-AZA STEROIDS. PART I

1962 ◽  
Vol 40 (11) ◽  
pp. 2153-2162 ◽  
Author(s):  
Ch. R. Engel ◽  
S. Rakhit
Keyword(s):  
Methyl Ester ◽  
Ethylene Glycol ◽  
Ethyl Acetate ◽  
Good Yield ◽  
Boron Trifluoride ◽  
Osmium Tetroxide ◽  
Periodic Acid ◽  
Boron Trifluoride Etherate ◽  
The Other ◽  
Other Hand

The smooth conversion of 3β-acetoxy-5α-pregnane-12,20-dione (IV), readily available from hecogenin (I), to Δ9(11)-3β,20β-diacetoxy-5α-pregnan-12-one (VIII) is reported. Ozonolysis of this product in ethyl acetate gave, in almost 90% yield, 3β-hydroxy-20β-acetoxy-9-oxo-9,12-seco-11-nor-5α-pregnan-12-oic acid (XI), further characterized by its ester derivatives XIa and XIb. The conversion of the seco acid XI to Δ8(9)-3β-hydroxy-20β-acetoxy-9-amino-9,12-seco-11-nor-5α-pregnen-12-oic acid lactam (12 → 9) (XII) and thence to Δ8(9)-N-acetyl-3β,20β-diacetoxy-11-aza-5α-pregnene (XIVa), the first 11-aza steroids to be known, is described. On the other hand, Δ9(11)-3β,20β-diacetoxy-5α-pregnen-12-one (VIII) is readily transformed to the 9α,11α-glycol VII with osmium tetroxide and thence, with periodic acid, to 3β,9α-dihydroxy-20β-acetoxy-11-oxo-11,12-seco-5α-pregnan-12-oic acid (X), characterized as the methyl ester Xa and diacetoxy methyl ester Xb, and easily converted to the acetoxy hydroxy keto dicarboxylic seco acid XIII. In the course of this work it is shown that, whereas ketalization of the saturated 12,20-diketone IV with ethylene glycol and boron trifluoride etherate gives a good yield of the 12-monoketal (in accordance with the reports of the literature), treatment of the analogous 16-unsaturated 12,20-diketone with the same reagents under the same conditions leads not to ketal formation but to addition of ethylene glycol in position 16.

Synthesis and Antifungal Activity of New Indolylthiazinone Derivatives

1998 ◽  
Vol 63 (1) ◽  
pp. 94-102 ◽  
Author(s):  
Milan Dzurilla ◽  
Peter Kutschy ◽  
Jalpa P. Tewari ◽  
Martin Ružinský ◽  
Stanislav Šenvický ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Intramolecular Cyclization ◽  
Boron Trifluoride ◽  
Alternaria Brassicicola ◽  
Alternaria Brassicae

New 6-(indol-3-yl)-5,6-dihydro-4H-1,3-thiazin-4-one derivatives were prepared by boron trifluoride catalyzed intramolecular cyclization of N'-substituted N-[3-(indol-3-yl)propenoyl]thioureas and by the reaction of 3-(indol-3-yl)propenoyl isothiocyanate with sodium hydrogensulfide. Antifungal activity of the prepared compounds was studied using the fungi Alternaria brassicae and Alternaria brassicicola.

Studies on the biosynthesis of the Chlorobium chlorophylls

1976 ◽  
Vol 273 (924) ◽  
pp. 255-276 ◽  
Keyword(s):  
Methyl Ester ◽  
Chlorophyll A ◽  
Alkyl Group ◽  
Biosynthetic Pathway ◽  
Chlorophyll Biosynthesis ◽  
Protoporphyrin Ix ◽  
Methyl Groups ◽  
Chemical Transformations ◽  
The Novel ◽  
Feeding Experiments

The Chlorobium chlorophylls (660) from Chloropseudomonas ethylicum are shown by 13 C n.m.r. spectroscopy and certain chemical transformations to be meso -methylated at the δ-position. Earlier work, which proposed that the meso -alkyl group was present at the α or β positions, is shown to be experimentally correct, but incorrectly interpreted. On the basis of 14 C and 13 C feeding experiments, the novel methyl groups in the (660) chlorophylls are shown to be derived from methionine in all cases. For most of the homologous mixture of (660) chlorophylls, the branch point from the biosynthetic pathway to chlorophyll a appears to lie between uroporphyrinogen III and coproporphyrinogen III; earlier workers had suggested that Chlorobium chlorophyll biosynthesis proceeded through magnesium protoporphyrin IX mono-methyl ester and possibly also via bacteriochlorophyll a or one of its immediate precursors. Evidence against this proposal, and a working hypothesis explaining feeding results, is presented. On the basis of this hypothesis, proposals for the structures of certain fractions of the (660) chlorophylls which are currently in dispute, are presented.

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