No abstract

No abstract

Poly-y-benzyl glutamates also exhibit association in solvents such as chloroform and dioxane; P.

Photoaddition reactions of chromone with different olefins and an acetylene have been carried out and the products identified. Photostability studies have shown that all of the 1 : 1 adducts are primary photoproducts. Competition experiments indicate that excited chromone is electrophilic in its reaction with extramolecular multiple bonds. Phosphorescence emission data indicates that the n + T* triplet state of chromone is involved in these reactions. This is supported by additional chemical evidence. The photoaddition reaction of chromone with 1,l-dimethoxyethylene indicates that orientational specificity can operate in these reactions. The mechanism of these reactions is probably best described as an electrophilic attack by C, of the n + T* chromone triplet on the olefin to give a 1P-diradical intermediate which closes to a cyclobutane. Products derived from initial hydrogen abstraction from the olefin by the carbonyl oxygen of excited chromone are also obtained.any examples of addition reactions of photochem-

filo Notes Yol. 11 Experimental Section15l- 2,3,.-A mixture of 100 g (0.38 mole) of diphenyl-4-pyridineniethanol, 100 ml of dioxane, and 50.5 g (0.40 mole) of MesSO* was heated on a steam bath for about 30 min, the solvent, was removed under vacuum, and the resulting residue was dissolved in f-PrOH. The pyridinium salt 1 was precipitated by addition of 1.5 vol of petroleum ether (bp 75-90°); 136 g, mp 169-171°. It was dissolved in a mixture of 1 1. of IT20, 2 1. of MeOII, and 50 ml of 50%: aqueous NaOH. The reaction flask was cooled in an ice bath and a solution of 77 g of NaBTL in 400 ml of II2() was added dropwise. Cooling was continued for 2 hr after which time the mixture was heated on a steam bath to allow evaporation of methanol. The product crystallized from the reaction mixture on cooling, was collected, washed (TLO), and recrvstallized from EtOAc to give 95.5 g (85% yield) of 2: mp 179-180.5°(lit.4b mp 179.0-179.8°); Xmax (MeOII) 248 my