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.

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.

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.

Preparation of 7-spiroepoxy and 7,7-disubstituted cephalosporanate 1,1-dioxide from 7-diazocephalosporanate 1,1-dioxide: Reactions of 7-diazocephalosporanate 1,1-dioxide with aldehydes

1991 ◽  
Vol 56 (11) ◽  
pp. 2352-2361 ◽  
Author(s):  
David Czajkowski ◽  
Oludotun A. Phillips ◽  
Narender A. V. Reddy ◽  
Paul Spevak ◽  
Bruce Lix ◽  
...  
Keyword(s):  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Tert Butyl ◽  
Profound Influence ◽  
Carbonyl Products

The reactions of tert-butyl-3-acetoxymethyl-3-cephem-7-diazocephalosporanate 1,1-dioxide (I) with acetaldehyde, benzaldehyde, 2-thiophene caboxaldehyde, 3-thiophene carboxaldehyde, 2-furan carboxaldehyde, 3-furan carboxaldehyde and isobutyraldehyde have been studied. Use of boron trifluoride etherate as a catalyst for these reactions was found to accelerate the reactions markedly and to favour the formation of aldehydes rather than the ketones at C-7 position as the carbonyl product. The products obtained from these reactions and the ratios of carbonyl products to epoxides suggest that the R groups of the carbonyl component have profound influence on the reactions.

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