25144-04-1Relevant articles and documents
Synthesis of ω-chain-modified analogues of 7-oxaprostaglandins
Naoshima,Nakayama,Kondo,et al.
, p. 1123 - 1129 (1984)
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Stereochemistry of the cyclization of alkoxy-substituted 5-hexenyllithiums: Effect of solvent and lithium iodide on diastereoselectivity
Bailey, William F.,Jiang, Xinglong
, p. 3183 - 3194 (2007/10/03)
The stereochemistry of the cyclization of 4-methoxy-5-hexenyllithium, 4-(methoxymethoxy)-5-hexenyllithium, 4-tert-butoxy-5-hexenyllithium, and 3-methoxy-5-hexenyllithium, each of which was generated from the corresponding iodide by low-temperature lithium-iodine exchange, has been studied in a variety of solvent systems. The results of these studies demonstrate that the stereochemical outcome of the cyclizations of alkoxy-substituted 5-hexenyllithiums may be profoundly affected by the medium in which the ring closures are conducted. The etiology of these often dramatic solvent effects is attributed to the ability of certain lithiophilic ligands to competitively complex the lithium iodide salt that is present as a co-product from the exchange reaction used to prepare the organolithiums.
Lewis base-catalyzed addition of trialkylaluminum compounds to epoxides
Schneider, Christoph,Brauner, J?rg
, p. 4445 - 4450 (2007/10/03)
A novel concept for catalytic epoxide alkylation has been developed. Lewis bases like phosphanes, arsanes, stibanes, and sulfides were found to catalyze the alkylation of symmetrical epoxides with trialkylaluminum compounds very effectively at a 5 mol % level. Cyclic as well as acyclic epoxides were readily alkylated in good yields. In reactions with terminal epoxides a significant enhancement of rate and/or regioselectivity was noted in the Lewis base-catalyzed process. Coordination of the Lewis base to the Lewis acidic aluminum reagent was proved by 27Al and 31p NMR spectroscopy and is proposed to form a more nucleophilic alkylating agent.
Generation and reactivity of oxazolidinone derived N-acyl radicals
Keck, Gary E.,Grier, Mark C.
, p. 1657 - 1659 (2007/10/03)
The N-acyl(phenylseleno)oxazolidinone 5 was prepared (85% yield) by treatment of the lithium salt of oxazolidinone with triphosgene, followed by addition of benzeneselenol. Reduction of 5 with n-Bu3SnH/AIBN gave the N- formyloxazolidinone 6 (99%) and reaction with allyltri-n-butylstannane gave 7 (89%). Bimolecular additions to various alkenes using the N-acyl radical derived from oxazolidinone 5 were also studied. Best results were obtained with electron rich olefins, such as enol ether derivatives. Eight such additions are reported, with yields ranging from 51-90%. Two prochiral substrates showed significant levels of diastereoselectivity in reactions with 5/Bu3SnH.
