Cleavage of unsaturated .alpha.-ketols to .omega.-oxo-.alpha.,.beta.-unsaturated acids
摘要:
Sodium periodate is a better reagent than sodium bismuthate, manganese dioxide, or lead tetraacetate for the cleavage of unsaturated alpha-ketols and affords omega-oxo-alpha,beta-unsaturated acids in good yield. The combination of this cleavage reaction and a rhodium(I)-mediated decarbonylation of omega-oxo-alpha,beta-unsaturated esters derived from polycyclic systems provided an enantioselective synthesis of cyclic systems bearing contiguous quaternary centers where one of the centers possessed gem-dimethyl groups.
A quick and easy way to produce tricycles related to the core structure of taxanes has been achieved using a palladium‐catalyzed domino reaction (see scheme, Bz=benzoyl). These studies have been performed with function‐oriented synthesis in mind. An efficient route for the construction of new taxane scaffolds that could be decorated with various groups to achieve activities comparable or superior to
Selective cleavages of one double bond in various 1,3-cyclic dienes were studied. It was found that the regioselectivity of fragmentation of the resulting primary ozonides depends on the size of the rings.
Silacycle-Templated Intramolecular Diels–Alder Cyclizations for the Diastereoselective Construction of Complex Carbon Skeletons
作者:Paul R. Carlson、Alexander S. Burns、Emily A. Shimizu、Shilin Wang、Scott D. Rychnovsky
DOI:10.1021/acs.orglett.1c00340
日期:2021.3.19
The utility of the dioxasiline ring as a π-facial directing group in the intramolecular Diels–Alder cyclization is explored. An initial investigation of substrate scope demonstrates that the rigidity of this directing group delivers robust stereocontrol across a number of substrates, affording single diastereomers in moderate to good yields. A mechanistic investigation reveals that the reactive diene
Lanthanide induced intramolecular coupling of aldehydes and ketones with electron-deficient olefins
作者:Eric J. Enholm、Antigone Trivellas
DOI:10.1016/s0040-4039(01)80359-2
日期:1989.1
Aldehydes or ketones with a δ,ε-olefin bearing a conjugating electron-withdrawing group undergo reductive cyclization with samarium iodide to afford five-membered rings. Diastereoselectivities of > 250:1 have been obtained.
Total Synthesis of Amaminol A: Establishment of the Absolute Stereochemistry
作者:Esa T. T. Kumpulainen、Ari M. P. Koskinen、Kari Rissanen
DOI:10.1021/ol7022856
日期:2007.11.1
The first synthetic route to amaminol A with use of an organocatalytic intramolecular Diels-Alder reaction is reported. The absolutestereochemistry is proven with a crystallographic image of a cyclic carbamate of amaminol A.