2- Oxabicyclo heptanes

The role of thermoboxane antagonists is asthma treatment still remains uncertain. AA-2414 (41) oral administration to asthmatic subjects favorably attenuated their response to methacholine challenge [98]. Modification of a 7-oxabicyclo heptane of drug candidates by incorporation of a phenylene spacer in the a-chain afforded SQ 35,091 (42), which shows longer duration of action (tj/2 = 16 hr) [99]. GR 32191 (43) shows PGD2-induced bronchoconstriction in asthmatics at 80 mg PO [100],... 

The dicarboxylation of cyclic alkenes is a useful reaction. All-c.vo-methyl-7-oxabicyclo(2.2.1]heptane-2,3,5,6-tetracarboxylate (233) was prepared from the cyclic alkene 232 using Pd on carbon and CuCh in MeOH at room temperature with high diastereoselectivity[216]. The dicarbonylation of cyclopentene... 

Propylene oxide 1,2-Epoxypropane 2-Methyloxirane 2-Methyloxacyclopropane Cyclohexene oxide 1,2-Epoxycyclohexane 7-Oxabicyclo[4.1.0]heptane ... 

Tandem cyclization-cycloaddition of diazoketones in the synthesis of sesquiterpenes, possessing 7-oxabicyclo [2.2.1]heptane fragment 97F303. 

Derivatives of 7-oxabicyclo[2.2.1]heptane in nature and as useful synthetic intermediates 99T13521. 

The knowledge of the valence tautomerization of benzene oxides to oxepins12 prompted several groups to synthesize oxepins by dehydrohalogenation of 7-oxabicyclo[4.1.0]heptane derivatives. Numerous examples have been described for the base-catalyzed elimination of hydrogen bromide from the 3,4-dibromo-7-oxabicyclo[4.1.0]heptane system. The reaction products are usually obtained as mixtures of oxepin 1 and benzene oxide 2. The 2,7-bis(hydroxy-methyl)oxepin 1 p obtained by this route can be converted to the 2,7-dicarbaldehyde with man-ganese(IV) oxide.23... 

Dibromo-7-oxabicyclo[4.1.0]heptanes can be obtained by bromination of the respective 7-oxabicyclo[4.1.0]hept-3-ene, the monoepoxide of cyclohcxa-1,4-diene, and when submitted directly to the dehydrohalogenation reaction give products 3 and 4.2 149 150... 

Epoxyeyclohexanone has been prepared in 30% yield4 by epoxi-dation of 2-cyclohexen-l-one with alkaline hydrogen peroxide, using a procedure described for isophorone oxide (4,4,6-trimethyl-7-oxabicyclo[4.1.0]heptan-2-one).5 A better yield (66%) was obtained using f r/-butyl hydroperoxide (1,1-dimethylethylhydroperoxide) and Triton B in benzene solution.6 The procedure described here is simple and rapid. 

A review on fliran and its derivatives in the synthesis of other heterocycles was published <95CHE1034>. Furan decomposes on Pd(lll) at 300 K to form H, CO and CjH, which can dimerize to benzene at 350 K <96JA907>. Again, a considerable number of Diels-Alder reactions with furan and fiiran derivatives was reported. The synthesis of 2-pyridinyl-7-oxabicyclo[2.2.1]heptanes (e.g., 3, 4) was accomphshed via zinc chloride-mediated Diels-Alder reaction of furan with 2-vinylpyridines <96SL703>. 

S,4R)-CAMPHAN0YL CHLORIDE (2-Oxabicyclo[2.2.l]heptane-1-carbonyl chloride, 4,7,7-trimethyl-3-oxo-, (1S)-)... 

Oleoxyl chloride, ol3 Oleyl alcohol, ol2 Oleylamine, o9 o-Orthanilic acid, al 15 7-Oxabicyclo[2.2.1]heptane, c331b, e7 7-Oxabicyclo[4.1.0]heptane, e6 6-Oxabicyclo[3.1.0]hexane, elO Oxacyclopentane, t69... 

Enthalpy of Polymerisation of Endo-2-Methyl-7-oxabicyclo [2.2.1] heptane, F. Andruzzi, D.S. Barnes and P.H. Plesch, Die Makromolekulare Chemie, 1975,... 

A-Protected 5-aza-2-oxabicyclo[2.2.1]heptanes and their oxo analogs are usually prepared from 4-hydroxyproline or its derivatives in several steps [57JA185 71JHC53, 71N(L)(230)457, 71T961] however, 75 was obtained in a facile one-step transformation involving intramolecular dehydration... 

A structure proposed for the lycopodium alkaloid, annotinine, was a derivative of 7-azabicyclo[2.2.1]heptane, but this is incorrect, and no naturally occurring compound is known to contain this ring system. On the other hand, the 7-oxabicyclo[2.2.1]heptane ring system is present... 

Numerous references to derivatives of 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid as defoliants, herbicides, fungicides, etc., are cited in index volumes of Chem. Ahstr. since Vol. 46 (1952). 

Hoping to improve or to shorten our total synthesis of L-daunosamine, we explored the following reactions with 112 and 113, the adducts of the racemic 7-oxanorbomene derivative 47 + 48 to PhSeCl and PhSCl, respectively. Saponification of 112 and 113, followed by treatment with formalin, afforded ketones 114 and 115, respectively. Treatment of with tributyltin hydride in toluene/benzene (AIBN 1 - 2%, 80 °C) gave the key intermediate ( )-I03 in 69 % yield. Under the same conditions, 115 was reduced to ( )-I03 in 40 - 45 % yield. Raney nickel reduction of 115 afforded ( )-103 in 50 % yield together with 40 % of ( )-7-oxabicyclo[2.2.1]heptan-2-one. However, we found the multistep procedure 32 100 101 102 103 easier to scale up. Several intermediates in our synthesis do not have to be isolated. For instance, transfomation of 32 into 102 can be carried out in the same pot in 94 % yield. 

Endothall is a structural analogue of cantharidin (Fig. 20). Its mode of action is apparently inhibition of protein phosphatase(s). A struc-ture/activity relationship study demonstrated that the presence of the oxygen bridge and the location of the two carboxylic groups play important roles in the activity of the molecules. The unusual 7-oxabicyclo[2.2.1]heptane ring of endothal is similar to that of cinmethylin, another natural product-like herbicide for which the mode of action has also eluded scientists for many years. 

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