Hisako Kobayashi

Metal-catalyzed Intramolecular Cyclization of 2-Diazo-4-(4-indolyl)-3-oxobutanoic Acid Esters

Obtention de tetrahydro-1,3,4,5 oxo-4 benzo [cd] indolecarboxylates-3 par cyclisation en presence de Pd(OAc) 2 et de tetrahydro-3,6,7,8 oxo-7 cyclopenta [e] indolecarboxylates-6 par cyclisation en presence de Rh 2 (OAc) 4

Synthesis and chemiluminescence of 3,3-diisopropyl-4-methoxy-4-(2-naphthyl)-1,2-dioxetanes

Abstract Six isomeric 3,3-diisopropyl-4-methoxy-4-(2-naphthyl)dioxetanes ( 4 ) were synthesized and their F − -induced chemiluminescences were examined in DMSO. Dioxetane 4b is a new type of chemiluminecent substrate which affords intense flash light. The other isomeric naphthyldioxetanes ( 4c – 4f ) exhibit chemiluminescent properties in agreement with the ‘odd/even’ relationship.

SYNTHESIS OF 3-ALKOXY-3-ARYL-4,4-DIISOPROPYL-1,2-DIOXETANES AND THEIR BASE-INDUCED CHEMILUMINESCENCE

Abstract Low-temperature singlet oxygenation of 1-alkoxy-1-aryl-2,2-diisopropylethylenes ( 9 ) gives the corresponding 1,2-dioxetanes ( 10 ) in high selectivity. Dioxetanes ( 10 ) are thermally stable enough to permit handling at room temperature, though an alkoxy group affects significantly their thermal stability and the order of half-life is MeO i -PrO ⪢ tert -BuO. On treatment with tetrabutylammonium fluoride in DMSO, dioxetanes ( 10e - 10h ) bearing a m -siloxyphenyl decompose rapidly to emit intense blue light with Φ CL > 0.2 . For the base-induced decomposition of 10e - 10h , the order of rate of decomposition is MeO i -PrO tert -BuO.

Synthesis of 3,3-diisopropyl-4-methoxy-4-(siloxy-2-naphthyl)-1,2-dioxetanes and their F−-induced chemiluminescent decomposition

Abstract Six isomeric 3,3-diisopropyl-4-methoxy-4-(siloxy-2-naphthyl)-1,2-dioxetanes (3) were synthesized and their F−-induced chemiluminescencent decomposition were examined in DMSO. The ‘odd/even’ relationship in ΦCL holds for all the dioxetanes (3). On the other hand, the ‘odd/even’ relationship in emission half-lives t 1 2 is observed for dioxetanes (3c–3f) with a trigger on the ring B but not for dioxetanes (3a and 3b) with a trigger on the ring A.

Effect of allylic oxygen on the reaction pathways of singlet oxygenation: Selective formation of 1,2-dioxetanes from 1-alkoxymethyl-2-aryl-1-tert-butyl-2-methoxyethylenes

Abstract Olefins bearing an allylic oxygen 1 undergo 1,2-addition of singlet oxygen to afford exclusively the corresponding 1,2-dioxetanes 2 , whereas their methylene analogues 3 suffer competitively 1,2-addition and ene reaction. The reactivity of 1 preferring 1,2-addition is likely attributed to the steering effect by an allylic oxygen.

Synthesis of 3-alkoxymethyl-4-aryl-3-tert-butyl-4-methoxy-1,2-dioxetanes as a chemiluminescent substrate with short half-life emission

Abstract Treatment of 3-alkoxymethyl-3- tert -butyl-4-(3-tert-butyldimethylsiloxy)phenyl-4-methoxy-1,2-dioxetanes ( 2 ) with TBAF in DMSO gives intensive blue light emission (λ max = 463nm, Φ CL > 0.1) with short half-life ( t 1/2 6 ) cause chemiluminescence with far longer half-life. A dioxetane ( 11 ) bearing a phosphoryloxyphenyl is cleaved enzymatically by alkaline phosphatase to generate light with high intensity.

Singlet oxygenation of 1-aminomethyl-1-tert-butyl-2-methoxy-2-(3-methoxy-phenyl)ethylenes: Marked effect of allylic nitrogen on the reaction pathways and chemoselectivity

Abstract The character of an allylic nitrogen affects significantly the reaction pathways as well as the chemoselectivity in the singlet oxygenation of allylic amines ( 1, 5, 7 and 11 ). Secondary amines ( 1a, b ) undergo α-oxidation to give imines ( 2 ). A primary amine ( 1c ) and amides ( 7a-c ) undergo preferentially the 1,2-addition of singlet oxygen, whereas the singlet oxygenation of an imide ( 5 ) afforded selectively an ‘ene’ reaction product. For a lactum ( 11 ), the 1,2-addition and the ‘ene’ reaction of singlet oxygen occur concurrently.

Copper-Catalyzed Aerobic Oxidation of Methoxyphenols

Abstract A variety of methoxyphenols were selectively converted methoxy-p-benzoquinones by the use of copper-catalyzed aerobic oxidation.