Photoinduced transformations. 76. A four-step substitution of a carbonyl group of steroidal ketones by an oxygen atom. A new method for the synthesis of cyclic ethers

1985 ◽  
Vol 50 (14) ◽  
pp. 2489-2494 ◽  
Author(s):  
Hiroshi Suginome ◽  
Shinji Yamada
Keyword(s):  
Oxygen Atom ◽  
Carbonyl Group ◽  
New Method ◽  
Cyclic Ethers

On the regioselectivity of the condensation of stabilized phosphoylids with 3-substituted phthalic anhydrides

1989 ◽  
Vol 67 (4) ◽  
pp. 569-573 ◽  
Author(s):  
Livain Breau ◽  
Margaret M. Kayser
Keyword(s):  
Oxygen Atom ◽  
Transition State ◽  
Carbonyl Group ◽  
Lewis Base ◽  
Carbonyl Function ◽  
Deficient Phosphorus ◽  
Phthalic Anhydrides

Condensations of stabilized phosphorane 1 with 3-substituted phthalic anhydrides were investigated. The importance of various effects influencing regio- and stereoselectivity of these reactions is discussed. It is proposed that the oxygen atom on the substituents in position 3 can act as a Lewis base toward the electron-deficient phosphorus of the ylid. The resulting complexation stabilizes the transition state for the reaction at the ortho carbonyl group, thus offsetting the usual steric and "push" effects, which favour attack at the meta carbonyl function. Keywords: Wittig condensations, phthalic anhydrides, regioselectivity, stereoselectivity.

Notizen: Oxygen Incorporation in Cleavage of 18-Labeled 13-HydroperoxylinoIeyl Alcohol into 12-Hydroxy- (3Z)-dodecenal in Tea Chloroplasts

1986 ◽  
Vol 41 (3) ◽  
pp. 359-362 ◽  
Author(s):  
Akikazu Hatanaka ◽  
Tadahiko Kajiwara ◽  
Jiro Sekiya ◽  
Hiromitsu Toyota
Keyword(s):  
Oxygen Atom ◽  
Carbonyl Group ◽  
Oxygen Incorporation

The oxygen atom in the hydroperoxy group of 13-hydroperoxylinoleyl alcohol was primarily incorporated into the carbonyl group of 12-hydroxy-(3Z)-dodecenal but scarcely into n-hexanal during the incubation with tea chloroplasts.

INFRARED SPECTRA OF 2,6-DIMETHYL-4-PYRONE COMPLEXES

1961 ◽  
Vol 39 (6) ◽  
pp. 1184-1189 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Complex Formation ◽  
Oxygen Atom ◽  
Carbonyl Group ◽  
Lewis Acid ◽  
Frequency Band ◽  
Infrared Spectra ◽  
Donor Site ◽  
Carbonyl Oxygen ◽  
Acid Strength ◽  
Group A

The infrared spectra of 2,6-dimethyl-4-pyrone in solution, and in complexes with HgCl2, ZnCl2, BF3, SbCl5, and HBr have been recorded. A band at 1639 cm−1 in the free pyrone moves to progressively lower frequencies in the complexes as the Lewis acid strength increases, identifying this band as the carbonyl stretching frequency and the donor site as the carbonyl group. A higher-frequency band, at 1678 cm−1 in the free pyrone, moves to lower frequency on complex formation, but to a much smaller extent, and is to be identified with a stretching mode of the ring. The site of protonation in 2,6-dimethyl-4-pyrone salts has been unequivocally shown to be the carbonyl oxygen atom.

Ab initio calculations of the oxygen atom NMR shielding in the carbonyl group

1993 ◽  
Vol 203 (4) ◽  
pp. 404-408 ◽  
Author(s):  
Andrzej Barszczewicz ◽  
Michał Jaszuński ◽  
Karol Jackowski
Keyword(s):  
Oxygen Atom ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Carbonyl Group
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