99553-69-2

Upstream product

• 1608-27-1 1-phenylpenta-1,3-diene 
• 16721-45-2 triphenyl(phenylmethylene)phosphorane 
• 1608-27-1 ((1E)-penta-1,3-dien-1-yl)benzene 
• 3909-96-4 (1E,3E)-1-phenyl-1,3-pentadiene 

Downstream Products

• 583-05-1 1-phenylpentane-1,4-dione 
• 300346-91-2 (Z)-4-hydroxy-1-phenyl-2-penten-1-one 
• 300346-84-3 (E)-4-hydroxy-1-phenyl-2-penten-1-one 
• 34721-89-6 2-methyl-5-phenyl-furan 

Relevant academic research and scientific papers

Tetraphenylporphine-sensitized photooxygenation of (E,E)- and (E,Z)-1- aryl-1,3-pentadienes generating cis-endoperoxides

Photooxygenation of either (E,E)- or (E,Z)-1-aryl-1,3-pentadienes (1a- c) sensitized with tetraphenylporphine (TPP) in benzene gave almost all cis- endoperoxides (2a-c) (cis-3-aryl-6-methyl-1,2-dioxacyclohex-4-enes) in good yields. A time course study of photooxygenation of (E,Z)-rich dienes measured by 1H NMR showed that singlet oxygen added exclusively to (E,E)-dienes converted from (E,Z)-dienes by photoinduced isomerization, and both rates increased when electron-donating groups were attached to the aryl group. A concerted [4 + 2] cycloaddition mechanism is suggested by the exclusive formation of cis-endoperoxides from (E,E)-dienes, despite the small energy difference between cis- and trans-endoperoxides calculated by ab initio methods. Some experiments were made to explore the observed isomerization.

A concise route to β-cyclopropyl amino acids utilizing 1,2-dioxines and stabilized phosphonate nucleophiles

(Chemical Equation Presented) 1,2-Dioxines react with glycine-derived phosphonate nucleophiles via a multistep cascade reaction to give β-cyclopropyl amino acid derivatives in good yield with excellent control of the cyclopropane stereocentres. The cyclopropyl ketones were oxidized to the corresponding carboxylic esters using Baeyer-Villiger conditions. Standard deprotection protocols produced a series of known β-cyclopropyl amino acids that are selective and potent agonists or antagonists of the metabotropic glutamate receptors in excellent yields.

A new route to diastereonumerically pure cyclopropanes utilizing stabilized phosphorus ylides and γ-hydroxy enones derived from 1,2-dioxines: Mechanistic investigations and scope of reaction

A new chemical transformation for the construction of diversely functionalized cyclopropanes utilizing 1,2-dioxines and stabilized phosphorus ylides as the key precursors is presented. Through a series of mechanistic studies we have elucidated a clear understanding of the hitherto unknown complex relationship between 1,2-dioxines 1a-e, and their isomeric cis/trans γ-hydroxy enones (23 and 21a-e), cis/trans hemiacetals 24a-e, and β-ketoepoxides (e.g., 26), and how these precursors can be utilized to construct diversely functionalized cyclopropanes. Furthermore, several new synthetically useful routes to these structural isomers are presented. Key features of the cyclopropanation include the ylide acting as a mild base inducing the ring opening of the 1,2-dioxines to their isomeric cis γ-hydroxy enones 23a-e, followed by Michael addition of the ylide to the cis γ-hydroxy enones 23a-e and attachment of the electrophilic phosphorus pole of the ylide to the hydroxyl moiety, affording the intermediate 1-2λ5-oxaphospholanes 4 and setting up the observed cis stereochemistry between H1 and H3. Cyclization of the resultant enolate (30a or 30b), expulsion of triphenylphosphine oxide, and proton transfer from the reaction manifold affords the observed cyclopropanes in excellent diastereomeric excess. The utilization of Co(SALEN)2 in a catalytic manner also allows for a dramatic acceleration of reaction rates when entering the reaction manifold from the 1,2-dioxines. While cyclopropanation is favored by the use of ester-stabilized ylides, the use of keto- or aldo-stabilized ylides results in a preference for 1,4-dicarbonyl formation through a competing Kornblum-De La Mare rearrangement of the intermediate hemiacetals. This finding can be attributed to subtle differences in ylide basicity/nucleophilicity. In addition, the use of doubly substituted ester ylides allows for the incorporation of another stereogenic center within the side chain. Finally, our studies have revealed that the isomeric trans γ-hydroxy enones and the β-keto epoxides are not involved in the cyclopropanation process; however, they do represent an alternative entry point into this reaction manifold.

SENSITIZED PHOTO-OXYGENATION OF ACYCLIC CONJUGATED DIENES

Sensitized photo-oxygenation of a wide variety of acyclic 1,3-dienes was investigated.The 1,4-cycloaddition of singlet oxygen to acyclic conjugated dienes was closely related to the thermal Diels-Alder reaction in stereospecificity, and steric and electronic effects of substituents.Reactivity order of singlet oxygen toward conjugated dienes and isolated C-C double bonds was exhibited as follows: trisubstituted monoolefins > 2-substituted 1,3-dienes > disubstituted mono-olefins.