Steroids keto group

Huang-Minlon showed" thiil steroid keto groups at C. C, Cu. (, 7, and C21, can be reduced satlsfiictarlly by his procedure but that a C,i keto group remains... 

Synthesis of steroidal diazirines has led to some biologically active compounds (65JA2665). The observation that diazirines and their parent ketones are identical in smell (B-67MI50800), points to the possibility that a diazirine group may stand for a keto group vis-d-vis a receptor. 

The reaction of 9(1 l)-dehydro steroids with nitrosyl fluoride was studied by Grantz and Rosenthal in pursuit of an alternate source for the important 9a-fluoro-11-oxygenated steroids. As expected, reaction at the more hindered 9(1 l)-double bond proceeds more slowly than at either the 4- or 5-double bonds. After 10 days at 3°, 3 -acetoxy-5a-pregn-9(l l)-en-20-one (50) affords a 45% yield of the 9a-fluoro-ll-nitrimine (51). Other 9a-fluoro-ll-nitrimines were prepared and it was found that the presence of additional keto groups, particularly the 3-keto group gives rise to side products with a concomitant reduction in yield of the desired 9a-fluoro-ll-nitrimines. In the case of the A" -3-ketones the yield is reduced to 10 %. The steric hindrance... 

Several steroid olefins, especially A -steroids, do not give exclusive a-epoxidation. The a-oxirane usually predominates in the epoxidation mixture, its proportion varying from 50% to 90% or greater when either perbenzoic acid or monoperphthalic acid is employed. The claims that the ratio of a- to p-epoxide is high in compounds containing a keto group d or a j5-substituent at may be misleading since epoxidation of 17a,20 20,... 

Recent improvements in the total synthesis of steroids which give as the first tetracyclic products 19-norsteroids bearing a hydroxyl or keto group at C-17 have revived interest in the conversion of androstanes to pregnanes. 

In a special case involving a C-ring aza steroid, it was found that epoxida-tion of a A -20-keto grouping using a two-phase system (t-butyl alcohol-aqueous potassium hydroxide-30 % hydrogen peroxide) was much superior to the standard hydrogen peroxide-aqueous methanolic alkali conditions. 

Cyanogen azide is a useful reagent for conversion of pyrrolidine enamines of 3-keto steroids to A-norsteroids. " Ring contractions can be carried out in the presence of 17j5-hydroxy, 17j -acetoxy, 20-keto groups and isolated double bonds. In a typical procedure, 17j -hydroxy-5a-androstan-3-one (partial formula 8) is converted into the enamine (9) by pyrrolidine in benzene... 

Deuterated and tritiated tin hydrides have been used to prepare deuterated saccharides93 and tritiated steroids46 from alkyl bromides, (equations 68 and 69). It is important to note that isomerization has occurred at the chiral reaction centre in the saccharide reaction (equation 68). For the steroid, the tin hydride reaction is regiospecific, i.e. it only reacts at the more reactive bromide rather than the less reactive chloride site and does not react with the keto group, the hydroxyl group or the acetal group. 

Irradiation in air of the deoxycholic acid (DCA, 157) complex of indanone leads to oxidation of both the steroid and the guest, yielding 5- 3-hydroxy-DCA, 158, and optically active 3-hydroxyindanone (241). In the presence of air, irradiation of the DCA clathrates of isochromane, 159, and indene, 161, leads to reaction with oxidation of the host and of the allylic position of the guest to a keto group (e.g., 159 — 160 and 161 — 162).The detailed mechanisms of these oxidations remain to be elucidated. 

Betamethasone is the steroid represented by this structure. It is composed of a 3-keto group on ring A, an 11 p-hydroxyl group and a 17a-hydroxyl group on ring C and D respectively. 

Of several related steroids in the defensive secretion of dytiscid beetles, deoxycorticosterone was most effective. It deterred simfish from feeding in 94% of the tests. Other steroids (pregnolones) that differed only by lacking a keto group at one carbon atom were either intermediate or not active at all (Gerhart etal., 1991). 

In steroidal a-hydroxy ketones with the keto group in position 20 and the hydroxylic group in position 17, the hydroxy, and better still, acetoxy group is replaced by hydrogen on refluxing for 24 hours with zinc dust and acetic... 

Spiro-y-lactones. This anion (1) has been used to prepare steroidal 17-spiro-y-lactones (equation 1) by reaction of a 17-keto steroid at the y-position. The Sharpless oxidation step can be conducted in the presence of a A4-3-keto group. When the... 

DNS-hydrazine (5-dimethylaminonaphthalene-l-sulphonylhydrazine) reacts with the keto groups of keto steroids to form fluorescent hydrazones. The derivatives are separated by TLC and are quantitated by fluorimetry at 340 nm (excitation) and 525 nm (emission). 

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