Etianic acids

The combined aqueous washes are acidified with dilute hydrochloric acid and extracted with ethyl acetate. Evaporation of this extract yields 86 mg of 3a-hydroxy-ll-oxo-5j -etianic acid, mp 291-293° (dec.). 

All is not lost however because the periodic acid method is found to be quantitative for the determination of corticosteroid esters, if these are first hydrolysed using a quaternary base, e.g. tetramethylammonium hydroxide. The acidic products formed in the above side-reaction do not perturb the determination, since the optically active product of the periodate oxidation following the hydrolysis is similar to the etianic acid. 

Turning to recent syntheses which have involved the addition of extra carbon atoms to androstanes, an efficient sequence of reactions has been proposed for the conversion of a 17-keto-steroid into a 20-keto-steroid.78 The route is illustrated by the conversion of 3/3-hydroxyandrost-5-en-17-one into the 20/3-formyl intermediate (184 R = H) by means of methoxymethylenetriphenylphosphorane, followed by oxidation to the etianic acid (184 R = OH) using silver oxide it is... 

Similar arguments would explain the formation of the 17-methyl-etianic acids from the 2i-haIopregnan-20-ones. The... 

The c.d. of androstane-17-carboxylic acids (etianic acids) and their esters shows an increase in Ae with decreasing temperature. Results have been interpreted in terms of the conformational preference of the carboxy-group. 

The 17a-hydroxy-etianic acid (294) forms an acetonide [ dioxolone (295)] under catalysis by perchloric acid. " The same dioxolone was formed by oxidation of the triol-acetonide (296) with chromium trioxide-pyridine. The hydroxy-acid (297) also forms a dioxolone. These derivatives are hydrolysed by alkali, but... 

Resolving agents, see also 3j8-Acetoxy-A -etianic acid L-(+)-2,3-Butanedithiol Dehydroabietylamine. Velluz and ElieF survey methods and list agents and procedures for their preparation. Additional methods and agents are listed below. 

Oxidation of 18-benzoylaminoprogesterone (3) with chromium trioxide afforded as the main product the lactam (4) (etianic acid series) together with a smaller yield of the imine (5).5... 

Note The stem name etianic acid was proposed by the Subcommittee on Steroid Nomenclature of the National Research Council as a replacement for "etiocholanic acid" in Order to avoid tbe use of the same name for parent hydrocarbons of different carbon content J. Am. Chem. Soc. 74, 2817 0952),... 

The predominant reaction, under base catalyzed aerobic conditions, appears to be oxidative cleavage of the side chain to the corresponding etianic acid (XVI). Formation... 

Solvent mixtures of usual compositions can be used, depending on polarity or whether these so-called etianic acids (Cgo) are present in free or esterified form esters are suitable solvents or solvent components. 

As an example we may give the formation of the tricyclic ABD moiety (90) from the keto ester (89) (Scheme 31). The use of the intramolecular Michael reaction for the formation of ring D in the synthesis of etianic acid (92) for the intermediate (91) (Scheme 13) belongs to the same type of cyclization. 

At the same time, the syntheses from BD fragments described in the third section are mainly used for the production of model compounds and tricyclic intermediates. The only exception is the synthesis of etianic acids described in Scheme 83. 

The Birch reduction of compound (322) led to the keto acid (325), identical with the intermediate obtained in the synthesis of steroid compounds by the CD — B route (Chapter IV, Scheme 117). However, the low yield of this acid and the nonstereospecificity of the construction of ring A from it (cf. [44]) made it necessary to search for more convenient methods for passing from the acid (322) to the steroids. It was found possible by de-methylation and catalytic hydrogenation to obtain from (322) one isomer of the hydroxyacid (323), the methylation and oxidation of which gave the keto ester (324). Its cyanoethylation and subsequent hydrogenolysis led to the required lOjS-isomer of the diacid (327) [417], from which it was possible to obtain etianic acid (326) by epimerization at Cg and the formation of ring A (cf. Scheme 77). 

Erythropentulose, Cl Erythrose, Cl Erythroxydiol Y, T34 Erythrulose, C2 Eserine, K30 Ethambutol, A8 Ethanoanthracenes, X4-5 7-ethylideneglutamic acid, AlO 5j3-etianic acid, T49 Eucomic acid, A29 Eucommiol, A25 ... 

---