Cyclobutanone optically active

Spiroannulations with diphenylsulfonium cyclopropanide have also been performed with polycyclic systems. Optically active 4-methyladamantan-2-one (21b),7 and the all-ds configurated tetraquinanes 23,72 73 and 2574 reacted stereoselectively with formation of syn- and endo,enclo-configurated cyclobutanones 22b, 24 and 26, respectively. The last two products 24 and 26 have been further elaborated in a successful75 and a prospective74 synthesis of dodecahcdrane. 

It is reported that a cyclobutanone reacted with sodium hydrogen sulfite to give an adduct which reacted with an optically active amine. The amine salt was resolved to give enantiomer-ically pure compounds.329... 

I. Hanna, J. Pan, and J. Y. Lallemand, Optically active cyclobutanones from glycals Preparation and regioselective cleavage, Synlett p. 510 (1991). 

Similarly, photolysis of chromium complex (CO)5Cr=C(OMe)(c-Pr) in the presence of two equivalents of the optically active 3-ethenyl-6(S)-phenyl-2-oxazolidinone under 90 psi CO pressure produced in high regio- and diastereo-selectively the 3-oxazolidine-substitued (2i ,3S)-cyclobutanone, in optical purity of > 97% de (equation 75)148. 

These reactions lead to optically active products when an optically active phosphine is used in place of triphenylphosphine. Thus treatment of the enol of optically active 6 with pivaldehyde gives the aldol 7 in 98% isolated yield. The absolute configuration was confirmed by X-ray diffraction. Only one method is known at the present time for removal of the metal moiety. Thus oxidation of 7 with ferric chloride affords the optically pure cyclobutanone 8 in 70% yield. 

Hegedus, L.S., Bates, R.W., and Soderberg, B.C. (1991) Synthesis of optically active cyclobutanones by photolysis of chromium-alkoxycarbene complexes in the presence of optically active ene-carbamates. Journal of the American Chemical Society, 113, 923—927. 

The methylenecyclopropane oxide —> cyclobutanone rearrangement has been coupled with asymmetric epoxidation to give optically active cyclobutanones, a versatile synthetic intermediate, without loss of the original enantiopurity of the epoxides (Eq. 282) [646]. Both processes occurring in this transformation are promoted by the same titanium species. Representative results are shown in Eqs 283 [646] and 284 [647]. The versatility of these transformations obviously relies on the facile accessibility of optically active epoxides. 

Amido-substituted methylenecyclopropanes can be used in [2 + 2] photocycloadditions with chromium-alkoxycarbene complexes. (5)-3-(2-Methylenecyclopropyl)-4-phenyloxazolidin-2-one (14) was prepared from pentacarbonyl[A-phenylglycinyl(cyclopropyl)carbene]chro-mium(O) by ring closure with sodium hydride and diphenyl carbonate. Photolysis of a variety of chromium-alkoxycarbene complexes 15 in the presence of two equivalents of optically active enecarbamate under carbon monoxide produced optically active cyclobutanones. The cis- and trani-products, 16 and 17, were formed with a high degree of asymmetric induction at the position a to the oxygen. ... 

Monocyclic cyclobutanones 9 (Fig. 1) with alkyl, aryl, or carboxylato substituents at C3 gave under the usual catalytic conditions optically active lactones with only moderate enantiomeric excesses (up to 47% ee) [25]. Increasing the amount of pivaldehyde used in the catalysis led to higher yields without a significant decline in enantioselectivity. For instance, 3-phenylcyclobutanone (9, R= Ph) was converted to the corresponding (S)-lactone in 66% yield with either... 

Synthesis of Optically Active Cyclobutanones and y-Lactones from Chromium Carbene ComplexesC ]... 

Molybdenum and rhenium complexes have also been reported to promote the Baeyer-Villiger oxidation using O2. Although limited to cyclobutanones, Sharpless asymmetric epoxidation conditions have provided optically active lactones from hydroxymethylbutanone.35... 

J. W. Pan, I. Hanna, and I. Y. Lailemand, Optically active cyclobutanones from glycals. 2. Synthesis of chiral cyclobutane derivatives by tetrahydropyran ring-opening. Tetrahedron Lett. 32 7543 (1991). 

The thermal reaction of dialkyl-ketens and -allenes to yield alkylidenecyclo-butanones has been the subject of detailed studies by Bertrand et The reaction is regiospecific and stereoselective. Bond formation takes place between the central bond of the keten and the allene. Use of chiral allenes gives optically active alkylidene-cyclobutanones. With an allene of the R configuration (109), the newly formed chiral centre in the products, (110) and (111), also has the R configuration, irrespective of whether the product has an exocyclic olefinic residue of the E or Z configuration. 

The oxaspiropentane — cyclobutanone rearrangement has been used to prepare the previously unknown 2-acylcyclobutanones (43) and their mono-acetal derivatives (acetal of side-chain ketone),while a related rearrangement of cyclopropylmethanols (44) provides an entry into 2-vinylcyclobutanones (45). Chiral 2-methylcyclobutanones have been obtained from 1,3-dibromo-propanes by condensation with an optically active TosMIC derivative. ... 

In the reaction of the same ketene with optically active 1,3-dimethylallene, optically active and racemic [2+2] cycloadducts are obtained, indicating that the reaction is a stepwise process. Optically active 1,3-diphenylallene reacts with t-butylcyanoketene to give cyclobutanones with the -configuration. In contrast, reaction of the same ketene with optically active 1,2-cyclononadiene gives a 2 3 mixture of the E Z stereoisomeric cycloadducts. ... 

The conventional method to synthesize 23 required five steps starting from 1,4-benzoquinone and 1,3-cyclohexadiene four of the steps were used for functional-group manipulation (Scheme 8.5) [23]. Finally, it afforded only a racemic mixture that necessitated an additional resolution process in order to get an enantio-enriched or enantio-pure 23. Thus, the asymmetric alkene insertion of 3-(2-styryl)cyclobutanones significantly reduced the steps required for the synthesis of optically active benzobicyclo [2.2.2] octenones. 

Lee-Ruff, E., Wan, W.-Q., and Jiang, J. L., A novel approach toward the synthesis of chiral 2,3-dideoxy nucleosides and their carbocyclic analogues, /. Org. Chem., 59, 2114, 1994 see also Lee-Ruff, E., Jiang, J.-L., and Wan, W.-Q., Process of Preparation of Optically Active Nucleosides from Chiral Cyclobutanones, U.S. Patent No. 5580973, December 1996. 

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