Different Reaction Modes for the Oxidative Dimerization of Epoxyquinols and Epoxyquinones. Importance of Intermolecular Hydrogen-Bonding
摘要:
An oxidative dimerization reaction, involving the three successive steps of oxidation, 6pi-electrocyclization, and Diels-Alder reaction, has been experimentally and theoretically investigated for the three 2-alkenyl-3-hydroxymethyl-2-cyclohexen-1-one derivatives epoxyquinol 3, epoxyquinone 6, and cyclohexenone 10. Of the sixteen possible modes of the oxidation/6pi-electrocylization/Diels-Alder reaction cascade for the epoxyquinone 6, and eight for the cyclohexenone 10, only the endo-anti(epoxide)-anti(Me)-hetero and endo-anti(Me)-hetero modes are, respectively, observed, while both endo-anti(epoxide)-anti(Me)-hetero and exo-anti(epoxide)-anti(Me)-homo reaction modes occur with the epoxyquinol 3. Intermolecular hydrogen-bonding is found to be the key cause of formation of both epoxyquinols A and B with 3, although epoxyquinone 6 and cyclohexenone 10 both gave selectively only the epoxyquinol A-type product. In the dimerization of epoxyquinol 3, two monomer 2H-pyrans 5 interact with each other to afford intermediate complex 28 or 29 stabilized by hydrogen-bonding, from which Diels-Alder reaction proceeds. Theoretical calculations have also revealed the differences in the reaction profiles of epoxyquinone 6 and cyclohexenone 10. Namely, the rate-determining step of the former is the Diels-Alder reaction, while that of the latter is the 6pi-electrocyclization.
Palladium-catalyzed formylation of organic halides with carbon monoxide and tin hydride
作者:Victor P. Baillargeon、J. K. Stille
DOI:10.1021/ja00263a015
日期:1986.2
La formylation catalysee par le palladium d'une variete de substrats organiques (iodoarenes, halogenures benzyliques, iodures vinyliques, triflates de vinyles et halogenures allyliques) avec le tributylstannane et le monoxyde de carbone donne les aldehydes avec de bons rendements dans des conditions douces et tolere un certain nombre de groupes fonctionnels
La formylation catalysee par le palladium d'une variete de substrats Organics特定的团体名称
Synthesis of 3-substituted 2-cyclohexenones through umpoled functionalization
A new protocol to obtain 3-substituted 2-cyclohexenones, was developed by reversing the chemical reactivity of 2-cyclohexenone. One-pot synthesis of 3-substituted 2-cyclohexenones can be achieved by treatment of 3-phenylthiosilyl enol ether with a mixture of t-BuLi/HMPA that allows hydrogen-selective exchange in presence of reactive electrophiles such as aldehydes, ketones and alkyl halides. This affords
SUBSTITUTED FLUOROETHYL UREAS AS ALPHA 2 ADRENERGIC AGENTS
申请人:Chow Ken
公开号:US20080255239A1
公开(公告)日:2008-10-16
Therapeutic compounds, and methods, compositions, and medicaments related thereto are disclosed herein.
本文揭示了治疗化合物、方法、组合物和相关药物。
Non-linear optically active molecules, their synthesis, and use
申请人:McGinniss D. Vincent
公开号:US20080004415A1
公开(公告)日:2008-01-03
In one aspect, the present invention provides a hyperpolarizable organic chromophore. The chromophore is a nonlinear optically active compound that includes a π-donor conjugated to a π-acceptor through a π-electron conjugated bridge. In other aspects of the invention, donor structures and acceptor structures are provided. In another aspect of the invention, a chromophore-containing polymer is provided. In one embodiment, the chromophore is physically incorporated into the polymer to provide a composite. In another embodiment, the chromophore is covalently bonded to the polymer, either as a side chain polymer or through crosslinking into the polymer. In other aspects, the present invention also provides a method for making the chromophore, a method for making the chromophore-containing polymer, and methods for using the chromophore and chromophore-containing polymer.
Synthetic approaches to phomactins: Novel oxidation of homoallylic alcohols using tetra-n-propylammonium perruthenate
作者:Timothy J. Blackburn、Eric J. Thomas
DOI:10.1016/j.tet.2018.05.068
日期:2018.9
step in the synthesis was to be the epoxidation of this methylenecyclohexane that was hoped would lead to a 1-(hydroxymethyl)cyclohexene by rearrangement of the exocyclic epoxide, but the epoxidation was difficult to carry out regioselectively on advanced intermediates. However, oxidation of a 15-methylenebicyclo[9.3.1]pentadeca-3,7-dien-14-ol using tetra-n-propylammonium perruthenate and N-methylmorpholine-N-oxide