The reactions of some 5,6-Dihalogenocyclohex-2-ene-1,4-diones (1,4-Benzoquinone dihalides) in boron trifluoride diethyl etherate

1973 ◽  
Vol 26 (2) ◽  
pp. 333 ◽  
Author(s):  
RK Norris ◽  
S Sternhell
Keyword(s):  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Hydrogen Halides ◽  
Boron Trifluoride Diethyl Etherate ◽  
High Yields ◽  
Very High

Treatment of five 1,4-benzoquinone dihalides in boron trifluoride etherate gives very high yields of isomeric dihalogenohydroquinones. With the exception of the conversion of 5,6-dichlorocyclohex-2-ene-1,4- dione into 2,3-dichlorohydroquinone, which is a true keto-enol isomerization, these products arise through elimination of hydrogen halides followed by re-addition.

Enolic Ortho Esters. I. Preparation and Birch Reduction of Some Coumarinoid Ortho Esters

1989 ◽  
Vol 42 (8) ◽  
pp. 1235 ◽  
Author(s):  
DJ Collins ◽  
LM Downes ◽  
AG Jhingran ◽  
SB Rutschmann ◽  
GJ Sharp
Keyword(s):  
Carbon Tetrachloride ◽  
Acid Hydrolysis ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
High Yield ◽  
Ortho Ester ◽  
Birch Reduction ◽  
High Yields ◽  
Ortho Esters ◽  
Hydrolysis Of

Phenolic ortho esters such as 4′,4′-dimethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7b) and 4′,4′-dimethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (9c) were prepared in low yields by reaction of 2H-1-benzopyran-2-one (5) or 3,4-dihydro-2H-1-benzopyran-2-one (8a) with 2,2-dimethyloxiran in carbon tetrachloride in the presence of boron trifluoride etherate. 3,4-Dihydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxoan ] (9a) and the corresponding 7-methoxy compound (9e) were obtained in high yield by reaction of (8a) or its 7-methoxy analogue (8b) with 1,2-bis(trimethylsily1oxy)ethane (10) in the presence of trimethylsilyl trifluoromethane-sulfonate . Birch reduction of phenolic ortho esters such as (9c) and (9e) afforded the enolic ortho esters 4′,4′-dimethyl-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxola n] (11a) and 7-methoxy-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (llc) in high yields. Birch reduction of 4′,4′,5′,5′-tetramethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7c) gave a 1 : 3 mixture of 4′,4′,5′,5′-tetramethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[l,3] dioxolan ] (9d) and the corresponding 3,4,5,8-tetrahydro compound (11b). Acid hydrolysis of the enolic ortho ester (11a) gave 67% of 2-hydroxy-2-methylpropyl 3-(2-oxocyclohex-3-enyl) propanoate (20).

scholarly journals Synthesis of N-pentofuranosyl oxazolines and amides though the selective transformations of D-sugar acetonides

2021 ◽  
Vol 65 (5) ◽  
pp. 558-567
Author(s):  
G. G. Sivets ◽  
A. V. Sivets
Keyword(s):  
Lewis Acid ◽  
Boron Trifluoride ◽  
Selective Hydrolysis ◽  
Boron Trifluoride Diethyl Etherate ◽  
Potassium Hydrogen ◽  
High Yields ◽  
Neutral Conditions ◽  
Hydrolysis Of ◽  
Hydrolysis Reactions

The method for synthesis of N-pentofuranosyl oxazolines was developed from the protected 1,2-O-acetonides of D-xylofuranose, -ribofuranose, and -arabinofuranose using boron trifluoride diethyl etherate, acetonitrile, and potassium hydrogen difluoride. A possible mechanism of the catalyzed reaction of acylated acetonides with acetonitrile in the presence of Lewis acid was considered in terms of the activation and cleavage of the 1,3-dioxalane part of the xylose derivative fol- lowed by the conversions of intermediates to α-isooxazoline. The hydrolysis reactions of N-α-glycosyl oxazolines were stud- ied in the acidic and neutral conditions. N-α-xylofuranosyl acetamide derivatives were prepared in high yields as a result of selective hydrolysis of protected α-xylofuranosyl isooxazolines in the neutral conditions.

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.

Face-selective Diels–Alder reactions of (1R,5R)-3-formyl-6,6-dimethylbicyclo[3.1.1]hept-3-en-2-one

1994 ◽  
Vol 72 (9) ◽  
pp. 1883-1893 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Yanhong Li ◽  
Eric N.C. Browne
Keyword(s):  
Low Temperatures ◽  
Boron Trifluoride ◽  
General Type ◽  
Acid Catalysis ◽  
High Selectivity ◽  
Boron Trifluoride Etherate ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Very High

The stereofacially differentiated enone aldehyde 11 was chosen to study the effects of steric and electronic influence on the Diels–Alder reaction. Under Lewis acid catalysis, 11 adds to dienes at low temperatures at a reasonable rate. Yields of desired chiral adducts are good to high with zinc chloride and boron trifluoride etherate catalysis. In all cases only products of addition to the Re face of general type 27 were observed. The regiochemistry of the adducts is exclusively that predicted by the ortho and para rules. The stereochemistry shows a very high selectivity in favour of aldehyde-endo transition state products. Unusual byproducts were also obtained in some examples and mechanisms of these unexpected reactions are discussed.

Synthetic Approaches to the Angucycline Antibiotics. A Route to C-Glycosidic Benz[a]anthraquinones

2000 ◽  
Vol 53 (1) ◽  
pp. 15 ◽  
Author(s):  
Fleur L. Andrews ◽  
David S. Larsen ◽  
Lesley Larsen
Keyword(s):  
Ammonium Nitrate ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Diels Alder ◽  
Photochemical Oxidation ◽  
Ceric Ammonium Nitrate ◽  
Boron Trifluoride Diethyl Etherate ◽  
Synthetic Approaches ◽  
Selective Deacetylation ◽  
Angucycline Antibiotics

3-Deoxy-6′-hydroxy-13-norurdamycinone B (32a) and 3-deoxy-13-norurdamycinone B (32b) have been synthesized in eight steps from 5,8-dimethoxynaphthalen-1-ol (9) both in 28% overall yield. The key step in this approach is the boron trifluoride diethyl etherate promoted β-C-glycosylations of (9) and 1,3,4,6-tetra-O-acetyl-2-deoxy- and 1,3,4-tri-O-acetyl-2-deoxy-D-arabino-hexopyranoses (13) and (19). The solvent, acetonitrile, was essential for the success of these reactions. Acetylation of the C-glycosyl-5,8-dimethoxynaphthalen-1-ols (16) and (20) followed by oxidation with ceric ammonium nitrate gave C-glycosyl-5-acetoxy-1,4-naphthoquinone derivatives (21) and (23) in 63 and 49% overall yields from (9). Selective deacetylation of the C 5 acetoxy groups of (21) and (23) was achieved by treatment with boron trifluoride etherate in dichloromethane to give 3,4,6-tri-O-acetyl- 2-deoxy- and 3,4-di-O-acetyl-2,6-dideoxy-β-D-arabino-hexopyranosyl-5-hydroxy-1,4-naphthoquinones (24) and (25) respectively. The tetra-O-acetyl diborate promoted Diels–Alder reactions of (24) and (25) with (±)-(E)-1-acetoxy-3-(2-methoxyvinyl)cyclohex-2-ene (8) each gave a 1 : 1 mixture of diastereoisomeric cycloadducts which, upon treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene gave (1R*)-1-acetoxy-9-(3,4,6-tri-O-acetyl-2-deoxy-β-D-arabino-hexopyranosyl)- and (1R*)-1-acetoxy-9-(3,4-di-O-acetyl-2,6-dideoxy-β-D-arabino-hexopyranosyl)-8-hydroxy-1,2,3,4-tetrahydrobenz[a]anthracene-7,12-dione (30a) and (30b) respectively. Sequential deacetylation and photochemical oxidation of (30a) and (30b) gave the targets (32a) and (32b) respectively.

Amphiphilic Perfluoroalkylated Derivatives of Aliphatic Triols: Hemocompatibility and Effect on Perfluorocarbon Emulsion

2002 ◽  
Vol 67 (10) ◽  
pp. 1436-1448 ◽  
Author(s):  
Vladimír Církva ◽  
Robert Kaplánek ◽  
Oldřich Paleta ◽  
Milan Kodíček
Keyword(s):  
Chain Length ◽  
Hydroxy Group ◽  
Boron Trifluoride ◽  
Linear Chain ◽  
Perfluorocarbon Emulsion ◽  
Water Emulsion ◽  
Boron Trifluoride Diethyl Etherate ◽  
Primary Hydroxy Group ◽  
Derivatives Of ◽  
Very High

Two sets of amphiphilic perfluoroalkylated aliphatic triols were prepared in a two-step synthesis: a protected glycerol, 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane (1) and protected 2-hydroxymethyl-2-methylpropane-1,3-diol, 5-hydroxymethyl-2,2,5-trimethyl-1,3-dioxane (11) were fluoroalkylated with racemic 2-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)- (2), or 2-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)- (3) or 2-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluorononyl)oxirane (4) using boron trifluoride diethyl etherate as a catalyst to afford intermediates 5-7 and 12-14, which were deprotected by re-acetalization to the target triols HOCH2CH(OH)CH2OCH2CH(OH)CH2CF2(CF2)nCF3 (n = 2, 4, 6) 8-10 and (OHCH2)2C(CH3)CH2OCH2CH(OH)CH2CF2(CF2)nCF3 (n = 2, 4, 6) 15-17. Regioselectivity of competitive fluoroalkylation of propane-1,2-diol and butane-1,3-diol appeared to be considerably dependent on the catalyst up to 93 rel.% for the preferential fluoroalkylation at the primary hydroxy group. Hemocompatibility of the triols 8-10 and 15-17, which was very high for linear-chain amphiphiles 9 and 10, showed particular dependence on the starting triol and perfluoroalkyl-chain length. All amphiphiles 8-10 and 15-17 displayed very good compatibility with perfluorodecalin-Pluronic F-68 water emulsion.

Synthesis of o-isopentenylphenols

1971 ◽  
Vol 24 (11) ◽  
pp. 2355 ◽  
Author(s):  
J Hlubucek ◽  
E Ritchie ◽  
WC Taylor
Keyword(s):  
Phosphoric Acid ◽  
Zinc Chloride ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Stannic Chloride ◽  
Counter Ion

The effect of the solvent and the counter-ion on the ring alkylation of 3- and 4-methoxyphenols by isopentenyl bromide has been examined. Under strictly anhydrous conditions good and consistent yields of the o- isopentenylphenols were obtained with the combination potassium- toluene, but sodium-toluene was more convenient. ��� Boron trifluoride etherate was more satisfactory than stannic chloride, zinc chloride, or phosphoric acid in catalysing the condensation of 3- and 4-methoxy-phenols with 2-methylbut-3-en-2-ol to the corresponding o-isopentenylphenols. Aryl α,α-dimethylpropargyl ethers were partially hydrogenated to the corresponding α,α- dimethylallyl ethers which rearranged in boiling N,N-diethyl-aniline to o-isopentenylphenols in high overall yield.

scholarly journals Synthesis of 5,6,7,8-Tetrahydroquinolines by Thermolysis of Oxime O-Allyl Ethers in the Presence of Boron Trifluoride Etherate.

1993 ◽  
Vol 41 (7) ◽  
pp. 1297-1298 ◽  
Author(s):  
Junko KOYAMA ◽  
Tamaki OGURA ◽  
Kiyoshi TAGAHARA ◽  
Masaaki MIYASHITA ◽  
Hiroshi IRIE
Keyword(s):  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Allyl Ethers
Sign in / Sign up

Export Citation Format

Share Document