Cyclopropane carboxaldehyde

CyclopropanecarboxaUehytte. Dehydration of a mixture of cis- and froni-cyclo-butane-l,2-diol (I) with boron trifluoride n-butyl etherate at 230° yields cyclopropane-carboxaldehyde (2) in 65-80% yield. Dehydration of (I) with p-toluenesulfonic acid gives (2) in somewhat lower yields (66%)- ... 

Generation of Sulfur Ylides Julia Olefination and Related Processes. Recently, the modified Julia olefination, which employed certain heteroarylsulfones instead of the traditional phenyl-sulfones, has emerged as a powerful tool for alkene synthesis. Although the reaction was first reported with LDA, bases such as LHMDS, NaHMDS, and KHMDS are now commonly used. In addition, solvent as well as base counter-cation have been shown to markedly affect the stereochemical outcome of the olefination reaction. For instance, KHMDS was less selective than NaHMDS for the coupling between benzothiazoylsulfone (1) and cyclopropane carboxaldehyde (2) in toluene, furnishing a 3.7 1 ratio compared to a 10 1 ratio favoring the Z-isomer. However, both bases provided a 1 1 mixture of isomers when the reaction was run in DMF (eq 54). ... 

The main isomerization products of 2,3-dihydrofuran are cyclopropane carboxalde-hyde (reaction (1)) and propenyl aldehyde (reaction (2)) [76,77]. Propenyl aldehyde can be obtained also via isomerization of the product—cyclopropane carboxaldehyde (reaction (3)). Reactions (1) and (2) go directly from the reactant to the product via one transition state. Reaction (3) has one intermediate and two transition states. The transition state for the production of cyclopropane carboxaldehyde (reaction (1)) involves a C(sp )—O bond cleavage and formation of a new C=0 double bond with the second adjacent carbon atom, together with a C—C bond formation (Figure 6.12). 

The isomerization of cyclopropane carboxaldehyde to propenyl aldehyde involves an opening of the cyclopropane ring and H-atom shift to form a methyl group. The pathway for this process is very similar to the one that has been found for cyclopropane carbonitrile that has been described in Section 6.2.2. 

Synthesis and some properties ofgem-dichlorocyclopropane carboxaldehyde acetals and cyclopropane carboxaldehyde acetals. A. Kh. Khusid, G. V. Kryshtal, V. A. Dom-... 

Formyl carbene is preparable by a copper acetylacetonate-catalyzed decomposition of diazoacetaldehyde40. This new carbenoid species formed a cyclopropane-carboxaldehyde with a substituted olefin. A novel approach to 3-lactones of above 70% optical purity involves reaction of a carbonyl compound with a ketene (or with an acyl halide convertible to a ketene) in the presence of an optically active bose. Trichloroacetaldehyde reacts with ketene in the presence of brucine to form (+)-8 in the presence of (-)-l-phenyl-l-dimethylaminoethane, (-)-8 is formed. ... 

Tomislav Rovis of Colorado State University has reported (Angew. Chem. Ini. Ed. 2005,44, 3264) the diastereoselective Lewis acid-mediated 1,3-rearrangement of dihydrooxepins such as 10 to the cyclopentene carboxaldehyde II. It is particularly convenient that the precursor aldehyde 9 is also converted into 11 under the same conditions. As there are many ways to construct alkenyl cyclopropanes such as 9 with control of both relative and absolute configuration, this is an important addition to methods for the stereocontrolled construction of cyclopentanes,... 

The synthesis of isatisine A113 started with the formation of the tetrahydroftiran ring through a Lewis acid-catalyzed cycloaddition reaction of the chiral (5)-vinyl cyclopropane diester 23 and iV-tosyl-indole-2-carboxaldehyde 24 (Scheme 10.42) [40]. 

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