18-Norandrosta-8,11,13-trienes. Part I. 11-Hydroxy-derivatives

Hewett, C. L.; Gibson, Samuel; Gilbert, Iain M.; Redpath, James; Savage, David S.

doi:10.1039/p19730001967

Cited by 5 publications

(9 citation statements)

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“…Thus the A6-analogue of (1) [i.e. (lo)] was shown by Turner 6b to yield the caromatic ketone (7) upon treatment with formic acid. The yield in this two-step process from (1) was 38%.…”

Section: Resultsmentioning

confidence: 99%

“…11 It appears that aerial oxidation also occurred, as the minor products isolated consisted of ca. 10% each of the aromatic A4-ketone (7) 6b and A4p6-ketone (8) .66p12…”

Section: Resultsmentioning

confidence: 99%

“…No oxidation occurred in 10% trifluoroacetic acid in chloroform, the products being the trienones (4) and (6). With 100%) trifluoroacetic acid the aromatic ketone (7) was obtained in 40% yield, other products being the conjugated 0 4 (7 1 /'.& 0 " trienone (6), and a precursor of (6). The latter is tentatively given the structure (5) since it has only one vinyl proton (H-4, 6 5.8 p.p.m.).…”

Section: Resultsmentioning

confidence: 99%

“…We have raised the overall yield to over 80% by combining in a single reaction the generation of unsaturation and methyl migration. Thus the Sa,lla-epoxide (9) [obtained from (1) by m-chloroperbenzoic acid oxidation] smoothly yielded the c-aromatic product (7) on treatment with boron trifluoride-et her complex. This experimental result is explicable in the context of the known behaviour of other ga,lla-epoxides.…”

Section: Resultsmentioning

confidence: 99%

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Ring-c aromatic steroids. 17β-Methyl-18-norpregna-8,11,13-trienes

Cheung¹,

MCQUEEN²,

Vadasz³

et al. 1979

J. Chem. Soc., Perkin Trans. 1

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Boron trifluoride-diethyl ether converts 20a.21 -diacetoxy-9a.l1 a-epoxy-17a-hydroxypregn-4-en-3-0ne (1 8) into 20a. 21 -diacetoxy-l7~-methyl-l8-norpregna-4,8,11,13-tetraen-3-one (1 9). An analogous c-aromatic steroid is similarly obtained from 9a.11 a-epoxy-l7a-methyltestosterone (9). From (1 9), by modifications of ring A and the 17a-side-chain, a series of 17p-methyl c-aromatic steroids has been prepared. The 5p configuration of the 3-ketone (21 ), obtained stereospecifically by hydrogenation of the A4-3-ketone (1 9) is deduced from 13C and l H n.m.r. data. Some acid-catalysed transformations of 1 7a-methyl-As(11)-testosterone (1 ) are reported.GENERAL routes to ring-c aromatic steroids have been explored by us in a programme to study the pharmacological properties of such substances. The impetus for such work comes in part from the isolation from fungi of viridin, a c-aromatic steroid,l and its related meta-bolites2 This paper records work based on Wagner-Meerwein migration of methyl from C-13 to C-17 upon elimination of a 17a-hydroxy. Before we commenced work, several other methods had been in use, viz. C-13+ C-12 methyl m i g r a t i ~n , ~ total ~ynthesis,~ and transformation from c-aromatic diterpenes.5In recent years Turner and his co-workers,6 and Hewett et have described work involving elimination-migration of 17-alcohols of the 17-methylandrostane group. We chose to work on pregnanes and corticoids to produce c-aromatic steroids of the 17p-pregnane series with oxygen functions on a 17a side-chain. The product. Where an 1 l-oxo-, 11 p-hydroxy-, or 11 pacetoxy-function is present, thermodynamic factors tend to favour instead the A12(13)-product (Scheme 1). Our work (below) suggests that even in the presence of A9(11)-unsaturation, proton loss from the rearranged C-13 carbonium ion occurs initially from C-14. SCHEME 1 17a-Methyl-A9(11)-testosterone (1) chosen as a model gave rise, on acid treatment, to a variety of products, With acetic acid-l0M-hydrochloric acid (1 : l), the re-OAcTABLE 1 'H Chemical shifts (CDC1, solutions; p.p.m. from SiMe,; J and Wit in Hz) Compounds H-4

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“…Thus the A6-analogue of (1) [i.e. (lo)] was shown by Turner 6b to yield the caromatic ketone (7) upon treatment with formic acid. The yield in this two-step process from (1) was 38%.…”

Section: Resultsmentioning

confidence: 99%

“…11 It appears that aerial oxidation also occurred, as the minor products isolated consisted of ca. 10% each of the aromatic A4-ketone (7) 6b and A4p6-ketone (8) .66p12…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Ring-c aromatic steroids. 17β-Methyl-18-norpregna-8,11,13-trienes

Cheung¹,

MCQUEEN²,

Vadasz³

et al. 1979

J. Chem. Soc., Perkin Trans. 1

View full text Add to dashboard Cite

show abstract

“…31,32 From the synthetic point of view, the rearrangement of the C18-methyl group to afford D 13 -18-norsteroids allowed the introduction of a double bond at the C/D rings junction, along with migration of the angular methyl group to the 17b-position. This transformation has been used for aromatization of ring C of androstane [33][34][35][36] and pregnane compounds. 37 D 13 -Steroids have been reported as useful intermediates for a number of active compounds.…”

Section: Introductionmentioning

confidence: 99%