2/- -2/oxoethyl acetate

Bioassay-guided fractionation of a phytotoxic extract led to the isolation of two major phytotoxic agents (Fig. 8) characterized as 2 -(2 -hydroxy-4 -methylphenyl)-2 -oxoethyl acetate and designated with the trivial names of hofmeisterin (29) and 3 4 4tz 9rz -tetrahydro-6,7 -dimethylspiro [benzofuran-3(2//), 2 -pyrano [2, 3- ] benzofuran]-2, Aa -diol (30), along with several inactive compounds. 

Scheme 1. Synthesis of hofmeisterin (Reprinted from]NatProd 68, Perez-Vasquez A, Reyes A, Linares E, Bye R and Mata R, Phytotoxic agents from Hofmeisteria schaffneri Isolation and synthesis of 2 (2 -hydroxy-4 -methylphenyl)-2 -oxoethyl acetate, 959-962, 2005, with permission from ACS).

Chloro-2-oxoethyl acetate) see Acetoxyacetyl chloride p-Chlorophenol... 

A high level of activity continues in connection with the synthesis of antimalarial artemisinin analogues and congeners, in which the 1,2-dioxepane moiety is embedded. Recent examples include the syntheses of various 10-substituted deoxoartemisinins of type 123 (eg. R1 = Cl COMe) from dihydroartemisinin acetate, and of type 124 (eg. R2 = a-OH, R3 = Me), from Grignard reagent addition to 10-(2-oxoethyl)deoxoartemisinin . 

The saponification of acetoxy group and reacting of 3a-acetoxy-lip-ol-18-one-pregnane lip,18-lactone 17-diazoketone with acetic acid were carried out to afford acetic acid 3a,lip-dihydroxy-18,20-dione-pregnane lip,18-lactone 17-oxoethyl ether. 

The 3-keto-84 system is introduced by conventional methods, that is, by oxidation of the 3-hydroxy group to a 3-keto group with chromic oxide. Bromination at the 4-position, and finally dehydrobromination with dinitrophenylhydrazine or with lithium chloride in dimethylformamide were carried out to give acetic acid lip-hydroxy-3,18,20-trione-pregn-4-ene lip,18-lactone 17-oxoethyl ether. 

A solution of 460 mg of (+/-)-2a-(2-carboxy-2-formylethyl)-3p-hydroxy-5-oxo-ip-cyclopentaneheptanoic acid methyl ester 6-lactone, 5-cyclic ethylene acetal in 6 ml of methylene chloride and 4.4 ml of pyridine was treated with a 5% ozone-oxygen mixture at - 70°C until the mixture had persistent pale blue color. The excess of ozone was evaporated by bubbling nitrogen into reaction and the solvents were removed in vacuo. The residue was tirturaed with ether affording crystalline (+/-)-2a-(2-carboxy-2-oxoethyl)-3p-hydroxy-5-oxo-ip-cyclopentaneheptanoic acid methyl ester 6-lactone, 5-cyclic ethylene acetal, m.p. 114-116°C. 

To a stirred mixture of the above amine hydrochloride (55.0 g, 0.22 mole) and [[(2,4-dioxo-l-imidazolidinyl)imino]methyl]formyl chloride (42.0 g, 0.22 mole) was added a solution of 440 ml of dimethylformamide and 44 ml of pyridine. The mixture was stirred for 20 h and poured into 2 L of water. The solid was collected by filtration and washed with ethanol and ether to give 36.0 g (28%) of N-[2-(4-bromophenyl)-2-oxoethyl]-[[(2,4-dioxo-l-imidazolidinyl)-imino]methyl]formamide, melting point 267°-269°C (recrystallization from 2200 ml acetic acid). 

METHYL (S)-2-PHTHALIMIDO-4-OXOBUTANOATE 2H-ISOINDOLE-2-ACETIC ACID, 1,3-DIHYDRO-l, 3-DIOXO-a-(2-OXOETHYL)-, METHYL ESTER, (S)- (137278-36-5), 76, 123... 

In the reactions between the halogenated dialkyl (2-oxoethyl)phosphonates (216 X = halogen) and aryldiazonium salts in aqueous sodium acetate, loss of the CHO group occurs when X = Cl... 

METHYL (S)-2-PHTHALIMIDO-4-OXOBUTANOATE (2H-lsoindole-2-acetic acid, 1,3-dihydro-1,3-dioxo-a-(2-oxoethyl)-,... 

Propyl 4-[(diethylcarbamoyl)-methoxy]-3 methoxyphenyl acetate Benzene-acetic acid, 4-[2-(diethylamino)-2-oxoethyl]-3-methoxy-, propyl ester B.P.,... 

R,55,65,7R, 9R, 1IR, 13R, 15R, 16R)-15- [(6-Deoxy-2,3-di-0-methyl- 3-D-allopyranosyl)oxy]methyl -6-( 3,6-dideoxy-4-0-[2,6-dideoxy-3-C-methyl-4-0-(3-methylbutanoyl)-a-L-nfco -hexopyranosyl]-3- (dimethy lamino) -P-D-glucopyranosyl oxy)-16-ethyl-5,9,13-trimethyl-2,10-dioxo-7-(2-oxoethyl)oxacyclohexadeca-11,13-dien-4-yl acetate... 

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