Daniel Uguen

Syntheses a l'aide de sulfones : XXIII. Sur la selectivite de la synthese des sulfones Allyliques

Abstract The role of the palladium ligands on the yield and regioselectivity of the reaction of conjugated dienes with arenesulphinic acids (or of allylic acetates with sodium arenesulphinates) has been investigated. Arenesulphinic acids catalyse the isomerisation of allylic sulphones.

Diastereocontrol in the Synthesis of Models of Rings C and D of Phorbol: Directing Effect of an Ether Substituent on Lithium Carbenoid Mediated Cyclopropanation

The diastereocomplementarity of halo- and alkylcarbenes (paths a and b, respectively) was shown in the cyclopropanation reaction of 1. The conversion of 1 into 7,7-dimethylbicyclo[4.1.0]heptan-1,2-diols (±)-2 and (±)-3 represents an important transformation in a synthetic strategy towards phorbol derivatives. TBDMS=tert-butyldimethylsilyl.

Synthesis of substituted dibenzophospholes. Part 4. Chemical transformations of 4,6-diaryl-3,7-dialkoxydibenzophosphole 5-oxides

Studies of 4,6-diaryl-3,5,7-trimethoxydibenzophosphole 5-oxides reported here include (a) electrophilic substitution (chlorination, bromination, and nitration) in the dibenzophosphole ring system and in the aryl side-chains; (b) dealkylations of the ether groups at positions 3, 5, and 7; and (c) attachment of water-solubilizing groups to the oxygen atoms at positions 3 and 7.

Synthesis of substituted dibenzophospholes. Part 3. Synthesis of 4,6-diaryldibenzophospholes from m-quaterphenyls

Some observations on T. Cohens method for coupling 2-iodonitrobenzenes to 2,2′-dinitrobiphenyls are reported. A general method for making 2′,2″-di-iodo-m-quaterphenyls from the 2′,2″-diamines, reported in Part 2, features decomposition of the bis-diazonium iodomercurates to dibenziodolium iodomercurates and pyrolysis of the latter. The procedure can be used to prepare other aryl iodides. 2′,2″-Di-iodo-m-quaterphenyls, on successive treatment with butyl-lithium, phosphorus trichloride, water, and hydrogen peroxide, yield 4,6-diaryl-5-hydroxydibenzophosphole 5-oxides, three of which were prepared. The structures of two derivatives of these, 2,8-dichloro-3,7-di-(2-hydroxyethoxy)-5-methoxy-4,6-diphenyldibenzophosphole 5-oxide and 5-hydroxy-3,7-dimethoxy-4,6-di(4-methoxy-3,5-di-t-butylphenyl)dibenzophosphole 5-oxide, have been determined by X-ray crystallography and are reported in the Appendix.

Organic synthesis with sulphones. Part 14. Nucleophilic substitution on styryl sulphones; a new route to arylacetaldehydes

Condensation of sulphones with aromatic aldehydes in an alkaline medium readily gives β-hydroxy-sulphones which can be dehydrated to β-styrylsulphones. When these are treated with one molar equivalent of sodium alkoxides in dimethyl sulphoxide at room temperature, β-alkoxystyrenes are formed by ready nucleophilic substitution. Treatment of the hydroxy-sulphones directly with an excess of sodium methoxide leads to the corresponding dimethyl acetals. This is a new and potentially useful way to prepare arylacetaldehyde derivatives.