58564-88-8Relevant academic research and scientific papers
Acid-Catalyzed Hydrolysis of Bridged Bi- and Tricyclic Compounds. XXXII. 7-Oxa-2-oxobicycloheptane: Kinetics, Products and Mechanism
Lajunen, Martti,Kaitaranta, Esa,Dahlqvist, Martti
, p. 399 - 403 (2007/10/02)
7-Oxa-2-oxobicycloheptane (7-oxa-2-norbornanone) produces in concentrated (7 mol dm-3) aqueous perchloric acid ca. 31percent phenol and several other products, which are mostly substituted phenols.The activation entropy, the solvent deuterium isotope effect and the slope parameters (m) of the linear excess acidity plots support the bimolecular mechanism (A-2) for the hydrolysis, but the products are evidently formed via the 3-oxo-4-hydroxy-1-cyclohexyl cation, which is typical of the unimolecular mechanism (A-1).Thus the reaction probably takes place by the A-2 (carbocation) mechanism.The data are compared with those recently measured for 7-oxabicycloheptane and 7-oxa-5-oxo-2-bicycloheptene.
Norbornanes. Part 21. Bridging Strain in Norbornyl and Oxanorbornyl Cations
Flury, Peter,Grob, Cyril A.,Wang, Guang Yi,Lennartz, Hans-Werner,Roth, Wolfgang R.
, p. 1017 - 1024 (2007/10/02)
Further evidence is presented that the 2-norbonyl cation is stabilized primarily by C(2)-C(6) bridging, and that C(2)-C(7) bridging leads to prohibitive strain.Thus, a comparison of the heats of hydrogenation of nortricyclene 17 and bicyclo2,7>heptane 18 indicates that the strain energy of the latter is ca. 21.5 kcal/mol higher than that of 17.Furthermore, 6-exo-2-oxabicycloheptyl sulfonates 8 ionize with strong O(2) participation to the bridged oxonium ion 12.In contrast, 2-endo-7-oxabicycloheptyl sulfonates 11 ionize without O(7) participation to form the unbridged carbenium ion 15.
SYNTHESIS OF (+)- AND (-)-METHYL 8-EPINONACTATE AND (+)- AND (-)-METHYL NONACTATE
Warm, Aleksander,Vogel, Pierre
, p. 690 - 700 (2007/10/02)
n four synthetic steps, (+)- and (-)-methyl 8-epinonactate ((+)- and (-)-4) have been derived from (+)- and (-)-7-oxabicycloheptan-2-one ((+)- and (-)-9), respectively.The (+)- and (-)-maethyl nonactate ((+)- and (-)-3) were obtained from (+)- and (-)-4, respectively, by Mitsunobu displacement reactions.Optical resolution of (+/-)-9 via cromatographic separation of the corresponding N-methyl-S-alkyl-S-phenylsulfoximides 24 and 25 yielded the starting material (+)- and (-)-9, respectively.
EXPEDITIOUS SYNTHESES OF METHYL 8-epi-NONACTATE AND METHYL NONACTATE
Warm, Aleksander,Vogel, Pierre
, p. 5615 - 5616 (2007/10/02)
(+/-)-Methyl 8-epi-nonactate ((+/-)-4) and (+/-)-methyl nonactate ((+/-)-3) were derived from (+/-)-7-oxa-2-bicycloheptanone (6) in four and five synthetic steps, respectively.
''Naked Sugars''as Synthetic Intermediates. Total Synthesis of L-Daunosamine
Warm, Aleksander,Vogel, Pierre
, p. 5348 - 5353 (2007/10/02)
The ''naked sugars'' are optically pure synthetic intermediates.Their advantage compared with natural sugars is that they possess a number of unsubstituted carbon atoms that can be substituted stereospecifically through direct procedures. (1S,2R,4S)-2--7-oxabicyclohept-5-ene-2-carbonitrile ((+)-1) is an example of a ''nuked sugar''.Electrophilic reagents add to the C(5), C(6) double bond, giving the corresponding adducts where the electrophile substitutes the exo position of C(6) and the nucleophile the endo position at C(5).This principle was used to prepare (1R,4R,5R)-5-endo-chloro-7-oxa-2-bicycloheptanone (13), which was monomethylated stereoselectively in the exo position at C(3), giving (+)-(1R,3S,4R,5R)-5-endo-chloro-3-exo-methyl-7-oxa-2-bicycloheptanone (14).The latter was transformed stereospecifically indo L-daunosamine (3-amino-2,3,6-trideoxy-L-lyxo-hexose).The (-)-camphanic acid used to engender asymmetry was recovered at an early stage of the synthesis.
Oxygen Participation Induced by Increased Electron Demand
Lambert, Joseph B.,Larson, Eric G.
, p. 7546 - 7550 (2007/10/02)
cis,endo-7-Oxabicyclohepta-2,3-diyl dibrosylate (6) acetolyzes faster than its diexo isomer (exo/endo ratio of 0.68 at 25 deg C).In the corresponding monobrosylate series, the exo isomer acetolyzes more rapidly than the endo isomer (exo/endo ratio
ELECTROPHILIC ADDITIONS CONTROLLED BY REMOTE SUBSTITUENTS. TOTAL SYNTHESIS OF DAUNOSAMINE.
Warm, Aleksander,Vogel, Pierre
, p. 5127 - 5128 (2007/10/02)
A new route to daunosamine based on the stereospecific electrophilic addition to 2-acetoxy-7-oxabicyclohept-5-ene-2-carbonitrile is presented.
A Synthesis and Some Reactions of 7-Oxabicycloheptan-2-one
Moursounidis, John,Wege, Dieter
, p. 2473 - 2482 (2007/10/02)
Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro- and endo-2-chloro-7-oxabicyclohept-5-ene-2-carbonitrile (4) and (5).Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation.Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of α-chloro isocyanates yields 7-oxabicycloheptan-2-one (1) in preparatively useful amounts.Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration.Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo2,6>heptane.
