Cyclopropanol ring

The intermediate (2) was converted by several steps into prostaglandins Eg and However, the necessary opening of the cyclopropanol ring as one step in the... 

Isomerization of cyclopropanols. Ring opening of cyclopropanols gives enones on Pd-catalysis. Formation of a-methylene ketones is favored by the use of (dba)jPd2, molecular sieve 4A, and benzoquinone (reoxidant) in toluene. " ... 

Cyclopropanol ring from ethyleneketones and reverse reaction... 

Cyclopropanol ring. Ethereal iV butyllithium soln. added dropwise at room temp, to ethereal exo/eiido-7-bicyclo[4.1.0]heptyl y5-chloroethyl ether until the Gilman test (s. Synth. Meth. 13, 789) is positive, then poured into satd. NaHC03-soln. -> exo/endo-7-hydroxybicyclo[4.1.0]heptane. Y 94%. F. e. s. J. Paust and U. Schollkopf, Ang. Gh. 77, 262 (1965). 

The Buchner reaction resulted from his pioneering contribution to the reactions of arenes with a-diazoketones. Eduard Buchner (1860-1917) obtained his Ph.D. in Munich in 1888 under the supervision of Theodor Curtius (1857-1928). His graduate studies resulted in A New Synthesis of Trimethylene Derivetives, in which he demonstrated the existence of a cyclopropanol ring. As a postdoctoral researcher, Buchner synthesized pyrazole for the first time in 1891. Since then, Buchner had taken over and further developed the chemistry of doazoalkanes from his mentor Theodor Curtius. 

Five carbasugar phosphates (14)-(18) have been successfully synthesized in either D or L, a or p forms from D-quinic acid (13) (Scheme 4). This synthesis included a novel, highly diastereospecific Pd/C-catalyzed cyclopropanol ring opening, diastereoselective reduction, dihydroxylation, the Mitsunobu reaction, and/or the Myers reductive 1,3-rearrangement, which were employed to install the desired stereochemistry. 

Potassium hydroxide Cyclopropanol ring opening with and without skeletal rearrangement 663. OH... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

A similar ring expansion has been reported in the oxidation of cyclopropanol 225 with manganese(III) tris(2-pyridinecarboxylate) to generate the / -keto radical, which is allowed to add to the silyl enol ether 226 [124], The... 

Another example is the asymmetric synthesis of ( )-pinidine 208 and its isomers. These syntheses are achieved via asymmetric enolization, stereoselective cyclopropanation, and oxidative ring cleavage of the resulting cyclopropanol system (Scheme 5-68).123... 

Transformations of Cyclopropanols with Retention of the Cyclopropane Ring... 

An interesting application of a 1,2-disubstituted cyclopropanol in a seven-membered ring-annelation methodology has been developed by Cha et al. [82], The cyclopropanol 124, obtained from methyl 1-cyclopentenecarboxylate (123) and 4-(triisopropylsilyloxy)-butylmagnesium chloride, was converted to a 1,2-dialkenylcyclopropanol bis-silyl ether, which, by a subsequent facile Cope rearrangement, afforded the cycloheptadiene-anne-lated cyclopentane derivative 125 in 32% overall yield (Scheme 11.32). 

Progress has also been reported in applying titanium-mediated cydopropanation reactions as a key step in the preparation of natural products. For example, racemic stigmo-lone (8-hydroxy-2,5,8-trimethylnonan-4-one) 163, a pheromone of the myxobacterium Stigmatella aurantiaca, has been synthesized in 67% overall yield by the titanium-mediated hydroxycyclopropanation of 2-methyl-5-hexen-2-ol 161 with ethyl isovalerate 160 followed by base-induced ring-opening of the resulting 2-(3-hydroxy-3-methylbutyl)-1-isobutyl-l-cyclopropanol 162 (Scheme 11.41) [139]. 

---