Cleavage acetic anhydride

Hydrolysis of the azlactone leads to the acylaminooinnamic acid the latter may be be reduced catal3rtlcally (Adams PtOj catalyst 40 lb. p.s.i.) and then hydrolysed by hydrochloric acid to the amino acid. Alternatively, the azlactone (say, of a-benzylaminocinnamic acid) may undergo reduction and cleavage with phosphorus, hydriodic acid and acetic anhydride directly to the a-amino acid (d/ p phenylalanine). 

Ether cleavage can also be effected by reaction with acetic anhydride and Lewis acids such as BF3, FeCl3, and MgBr2.97 Mechanistic investigations point to acylium ions generated from the anhydride and Lewis acid as the reactive electrophile. 

A great number of transformations has been performed on narceine imide (116) by Czech researchers. Oxidation with potassium permanganate in acetone or with nitric acid caused the cleavage of the alkaloid, giving rise to hemipinic imide (127). A similar result was noted by Rdnsch (129,130) during Lemieux-Johnson oxidation of ene lactam 152 (129,130) in this reaction the basic component (156) was isolated as well. The use of hydrogen peroxide in acetone converted 116 to (Z)-narceine imide N-oxide, which under the action of acetic anhydride underwent N-dealkylation (135). 

The elaboration of 113 to (—)-kinamycins C, F, and J, is shown in Scheme 3.19. To access ( )-kinamycin C (3), the silyl ether function of 113 was cleaved with aqueous hydrochloric acid (95 %). Alternatively, treatment of 113 with lithium hydroxide served to liberate the phenol function and saponify the three acetate esters, to provide ( )-kinamycin F (6) in 92 % yield. Finally, acylation of the tertiary hydroxyl of 113 (acetic anhydride, triethylamine) afforded a tetraacetate. Cleavage of the silyl ether then provided ( )-kinamycin J (10) in 80 % over two steps. 

Transformations of Methyl 5-0-Benzyl-2-0-methyl-/3-I)-glueofuranosidurono-6,3-lae-tone (86) to Dimethyl (Z,E)-2-Methoxy-5-(phenylmethoxy)-2,4-hexadienedioatevl (87). ( Elimination employing DBU b oxidation with silver oxide-sodium hydroxide followed by diazomethane esterification c acidic glycoside cleavage, oxidation by dimethyl sulfoxide-acetic anhydride with formation of 5-0-benzyl-2-0-methyI-D-glucaro-1,4 6,3-dilactone, elimination by using DBU, followed by short treatment with diazomethane d elimination by DBU with subsequent diazomethane esterification e sodium borohydride in hexamethylphosphoric triamide 1 catalytic oxidation followed by short treatment with diazomethane " dimethyl sulfoxide-sulfur trioxide-pyridine-triethylamine.150)... 

Contrary to the stable azepines and diazepines, benzo[ 7]benzofuro[2,3-/][l,4]-oxazepine 272 undergoes ring cleavage under reductive conditions in the acetic acid/acetic anhydride to afford open chain acetoxy amine 273 (Scheme 58, Section 3.2.2 (2001JHC383)). 

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