Steroidal esters

Carbonylation of enol triflates derived from ketones and aldehydes affords Q,/)-unsaturated esters[332]. Steroidal esters are produced via their aryl and enol triflates[328]. The enol triflate in 477 is more reactive than the aryl tritlate and the carbonylation proceeds stepwise. First, carbonylation of the enol triflate affords the amide 478 and then the ester 479 is obtained in DMSO using dppp[333]. 

Aluminium oxide Strong Steroids, esters, alkaloids... 

S. Kaur, P. Khanna, S. S. Parmar, B. Ah, Selective Stimulation of Carboxylesterases Metabolising Charged Steroid Esters by Hydrocortisone , Biochem. Pharmacol. 1991, 41, 476-478. 

An alternative route to such 6-(l-hydroxyalkyl)-substituted pteridines including 106 is from 2,4,5-triamino-6-butoxypyrimidine 107 and 2-formyloxiranes 108 in which the stereochemical properties are emphasized by the inclusion of the 17-steroidal ester <1992S303>. L-Biopterin 106 was synthesized from the oxirane 108 and 107 via a 5,6-dihydropteridine intermediate which was oxidized in situ to afford the product (Scheme 21). Syntheses of oxiranes and the condensation mechanism in the context of molecular orbital calculations were discussed. The field has been reviewed <1998H(48)1255>. 

A typical example is alkylation of the steroid ester 11. Treatment of 1 with LDA in tetrahydrofuran at —78 °C for 1 hour followed by addition of 4-bromo-2-methyl-2-butene in the presence of HMPA at —78 °C to —20 °C furnished an 87 13 mixture of the monoalkylated esters 3a and 3b. The potassium enolate 2 (KHMDS, THF, —78 °C, 1 h) has been hydroxylated with an oxaziridine reagent in 70% yield to give a 3 1 mixture of a-hydroxy derivatives. 

A representative of the second group is the hydrolysis of 3,5-dinitro-benzoic acid esters of hydroxysteroids. The waves of the nitro-groups in the steroid ester are significantly smaller than those of 3,5-dinitrobenzoic acid, and the hydrolysis has been followed by the increase in the wave-height with time (18). 

GC unit. Peak identification is as follows 1, benzylalcohol 2, testosterone propionate 3, testosterone isocaproate 4, testosterone phenylpropionate 5, testosterone decanoate 6, oil matrix (b) GC analysis of the transfer (4 pd) from the micro SEC system (c) Direct GC analysis of a standard solution of the steroid esters. Reprinted from Proceedings of the 10th Symposium on Capillary Chromatography, M. Ghys et al, On-line micro size-exclusion chromatography-capillary gas chromatography, 1989, with permission from Wiley-VCH. 

DEGS for alcohols, aldehydes, ketones, amino acids, essential oils, steroids, esters, phosphorus and sulfur compounds... 

The solvent extracts can be cleaned up by traditional column chromatography or by solid-phase extraction cartridges. This is a common cleanup method that is widely used in biological, clinical, and environmental sample preparation. More details are presented in Chapter 2. Some examples include the cleanup of pesticide residues and chlorinated hydrocarbons, the separation of nitrogen compounds from hydrocarbons, the separation of aromatic compounds from an aliphatic-aromatic mixture, and similar applications for use with fats, oils, and waxes. This approach provides efficient cleanup of steroids, esters, ketones, glycerides, alkaloids, and carbohydrates as well. Cations, anions, metals, and inorganic compounds are also candidates for this method [7],... 

Kll. Kohen, F., Kim. J.-B., Barnard, G., and Lindner, H. R., Antibody-enhanced hydrolysis of steroid esters- Biochim. Biophys. Acta 629, 328-337 (1980). 

Generally speaking the classical alkaline hydrolysis reaction followed by back-titration could be used to determine steroid esters. The results for 21-acyloxycortico-steroids (where R = H, OH) are however quite unsatisfactory. The reason behind the unacceptable result is the auto-oxidation of the a-ketol side-chain in an alkaline medium. Because of the formation of acidic products in side reactions, there is an over consumption of base in the titration and a corresponding over determination of the amount of steroid. 

With inflexible substrates, this photochemical functionalization process showed significant selectivity. As our first example, photolysis of steroid ester 70 led to carbonyl insertion into the C-H bonds at C-7 and C-14 [149,150]. Other steroid esters afforded selective functionalizations in various positions [e.g. 151, 152], and compound 71 directly dehydrogenated the steroid to form the product olefin 72 [150]. 

Photochemical functionalizations with synthetic potential have been achieved using benzophenone esters of steroids (Scheme 10). In some cases attack occurs on several hydrogens for instance, a mixture of and A -alkenes is produced on irradiation of (2). However, with compound (3) photolysis produces only (4) as a new steroid. The yield of 55% involves some photoreduction of the benzophenone unit by solvent, so the other significant product is starting material with a reduced ketone group. Many other photolyses of benzophenone steroid esters have been studied they lead to useful infoimation about conformations, but not the directed single-site functionalizations that would make them synthetically useful. 

Nuclear magnetic resonance spectroscopy can be used to distinguish between the phosphate esters of steroids. The free steroids can be distinguished by infra-red spectrophotometry, but the phosphate esters are sufficiently polar to give rise to absorption bands that dominate the IR spectra and make distinction difficult. The NMR spectra of these steroid esters are not subject to this interference, and although they may be very difficult to interpret, they do provide the necessary distinction. 

S Aim et d, The use of C NMR Spectroscopy m Forensic Drug Analysis, Forens Set Fit, 1982, 79, 271-280 British Pharmacopoeia, Vols 1 and II, London, HMSO, 1980 (Identification of Steroid Esters and the Examination of Aimnoglycoside Antibiotics)... 

Pyrolysis of steroid esters, particularly benzoates, has been used as a method for the preparation of olefins [143]. The reaction involves a cis hydrogen atom stereospecifically and is interpreted in terms of a cyclic transition state of essentially non-ionic character (i). The specificity of the reaction is such that 5a-cholestan-4jS yl benzoate (2) gave only the A -olefin (3) [118], whereas the epimeric 4a-benzoate (4) gave the... 

Steroid and steroid esters Cholate, deoxycholate, taurocholate, glycocholate, taurodeoxycholate, sodium taurodihydrofusidate, and cholesterol esters... 

Most allylic oxidations of methylene to carbonyl groups are carried out by chromic oxide [552, 555] or its complexes with pyridine [593, 606] and performed on steroidal esters [552, 593, 606] and ketones [61, 552] (equation 130). 

C and A are new bases from Stephanotis steroidal esters of y-methylanthranilic on spectral evidence, is assigned structure and sterochemistry represented by (95) (S. Terada et at.. Tetrahedron Letters, 1978, 1995). The latter on total hydrolysis affords the known steroid sarcostin (96), and a careful analysis of its pmr- and C-nmr-spectra, with appropriate comparisons with model esters derived... 

P6. Pasqualini, J. R., Cedard, L., Nguyen, B. L., and Alsatt, E., Differences in the activity of human term placenta sulphatases for steroid ester sulphates. Biochim. Biophys. Acta 189, 177-179 fl967). 

Organo-tin and -silicon steroids have been prepared from 3a- and 3)S-halocho-lest-anes and 5-enes, and a number of steroidal esters of p-[AfAT-bis(2-chloro-ethyl)amino]phenylacetic acid and sulphides derived from p-bis(2-chloroethyl)-amino-thiophenol and ethylenimine derivatives of steroids have been prepared. The substituted phenylacetates showed good inhibition of certain tumours. ... 

Saponification of steroid esters can also be steered with Candida cylindracea lipase (CCL),272, 273]. This process occurs in the presence of octanol in organic solvents and is characterized by a pronounced stereospecificity and regioselectivity. Thus, the 3a-... 

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