Bridged-ring steroids. II. The synthesis of bridged steroids with a bicyclo[2.2.1]heptane ring A system

Yates, Peter; Winnik, Françoise M.

doi:10.1139/v81-243

Cited by 14 publications

(3 citation statements)

References 18 publications

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“…Thus, 6β-hydroxy-3α,5-cyclo-5α-androstan-17-one (149), and other analogues (150, 151 and 158) were synthesized as steroidal blood pressure-lowering hormones [160,161]. Cyclosteroids (152 and 153), which show an anabolic effect, were synthesized from 19-nor steroids, and would be of great interest for sports medicine as representatives of anabolic steroids [162,163], although other cyclosteroids (154)(155)(156)(157) were synthesized as potential agents with antitumor properties [164][165][166].…”

Section: Sterols and Triterpenoids With Cyclopropane Ring In The Side Chainmentioning

confidence: 99%

“…Several steroids , containing an additional 5-or 6-membered ring (s) in the steroid molecule, have been synthesized in various laboratories and demonstrate a wide range of biological activities [18,160,161,164,167,168,210,[227][228][229][230][231][232], and their structures are shown in Figures 18 and 19. Their pharmacological profile is presented in Tables 16 and 17.…”

Section: Miscellaneous Cyclosteroids and Triterpenoids Derived From Marine And Terrestrial Sourcesmentioning

confidence: 99%

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Antitumor Profile of Carbon-Bridged Steroids (CBS) and Triterpenoids

2021

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This review focuses on the rare group of carbon-bridged steroids (CBS) and triterpenoids found in various natural sources such as green, yellow-green, and red algae, marine sponges, soft corals, ascidians, starfish, and other marine invertebrates. In addition, this group of rare lipids is found in amoebas, fungi, fungal endophytes, and plants. For convenience, the presented CBS and triterpenoids are divided into four groups, which include: (a) CBS and triterpenoids containing a cyclopropane group; (b) CBS and triterpenoids with cyclopropane ring in the side chain; (c) CBS and triterpenoids containing a cyclobutane group; (d) CBS and triterpenoids containing cyclopentane, cyclohexane or cycloheptane moieties. For the comparative characterization of the antitumor profile, we have added several semi- and synthetic CBS and triterpenoids, with various additional rings, to identify possible promising sources for pharmacologists and the pharmaceutical industry. About 300 CBS and triterpenoids are presented in this review, which demonstrate a wide range of biological activities, but the most pronounced antitumor profile. The review summarizes biological activities both determined experimentally and estimated using the well-known PASS software. According to the data obtained, two-thirds of CBS and triterpenoids show moderate activity levels with a confidence level of 70 to 90%; however, one third of these lipids demonstrate strong antitumor activity with a confidence level exceeding 90%. Several CBS and triterpenoids, from different lipid groups, demonstrate selective action on different types of tumor cells such as renal cancer, sarcoma, pancreatic cancer, prostate cancer, lymphocytic leukemia, myeloid leukemia, liver cancer, and genitourinary cancer with varying degrees of confidence. In addition, the review presents graphical images of the antitumor profile of both individual CBS and triterpenoids groups and individual compounds.

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Section: Sterols and Triterpenoids With Cyclopropane Ring In The Side Chainmentioning

confidence: 99%

Section: Miscellaneous Cyclosteroids and Triterpenoids Derived From Marine And Terrestrial Sourcesmentioning

confidence: 99%

Antitumor Profile of Carbon-Bridged Steroids (CBS) and Triterpenoids

2021

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“…For example, 2,5-carbon-bridged steroids of type 1 have been obtained by introduction of the bridge into a steroid precursor via an ene reaction (3). We now report on the total synthesis of 1,4-carbon-bridged steroids of type 2 via a modified Torgov reaction sequence.…”

Section: Introductionmentioning

confidence: 99%

Bridged-ring steroids. V. The total synthesis of 1,4-methano steroids by a modified Torgov sequence

Yates¹,

Douglas²,

Datta³

et al. 1988

Can. J. Chem.

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The Diels–Alder adduct, 17, of cyclopentadiene and 2-methoxy-5-methyl-1,4-benzoquinone was reduced with sodium borohydride to the ketol 18, whose acetate 19 was further reduced with zinc amalgam to the monoketone 20. Reaction of 20 with vinyllithium gave the allylic alcohol 21, which underwent very ready dehydration with rearrangement to give the tricyclic enol ether 27, which was hydrolyzed to ketone 28a. Hydrogenation of 19 gave the dihydro product 30, which was reduced with zinc amalgam to the ketone 31. Treatment of the latter with vinyllithium gave the allylic alcohol 32. This was more stable than its analogue 21, but underwent hydrolysis and dehydration to the dienone 33. Treatment of 32 with 2-methyl-1,3-cyclo-pentanedione (5) in the presence of Triton B gave the tricyclic intermediate 35, its hydrolysis product 36, and the hydroxy derivative of the latter, 37. In the absence of base, 32 and 5 gave largely product 36. Hydrogenation of 36 gave the dihydro product 38, which on treatment with methanolic potassium hydroxide gave (±)-(1β,4β,5β,8α,9β,10β,13β,14β)-14-hydroxy-1,4-methanoandrostane-7,17-dione (39). Dehydration of 39 with p-toluenesulfonic acid gave first (±)-(1β,4β,5β,9β,10β,13β)-1,4-methanoandrost-8(14)-ene-7,17-dione (40), which was converted in turn to (±)-(1β,4β,5β,8α,9β,10β,13β,14β)-1,4-methanoandrost-15-ene-7,17-dione (41). Similar dehydration of 36 gave (±)-(1β,4β,5β,10β,13β,14β)-1,4-methanoandrosta-8,15-diene-7,17-dione (45).

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Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

1992

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Well over a decade ago, two reviews were contributed to the Organic Reactions series covering substitution and conjugate addition reactions in organocopper chemistry. Their appearance, which highlighted most of the early work in this field, served not only as a source of invaluable references to original literature reports, but also stimulated a vast number of subsequent studies on the properties and uses of organocopper complexes. The work cited in this chapter, which dates from ca. 1975, concerns in large measure uses of organocopper complexes originating from either catalytic or stoichiometric quantities of a copper(I) halide together with a Grignard (RMgX) or organolithium (RLi) reagent. These combinations form either neutral organocopper reagents RCu ( 1 ) or copper(I) monoanionic salts R 2 CuM (M = Li or MgX), commonly referred to as “lower‐order” species. The latter ate complexes with lithium as gegenion ( 2 ) are also known as “Gilman reagents” in recognition of their origins. Copper(I) cyanide is also an excellent precursor, affording homogeneous mixtures of lower order cyanocuprates RCu(CN)Li, ( 3 ), upon treatment with an equivalent of an organolithium. The strength of the CuCN linkage presumably accounts for direct cuprate formation with 1 equivalent of the organolithium, rather than the metathesis that occurs with copper(I) chloride, bromide, or iodide. While use of reagents ( 1 ), ( 2 ) and ( 3 ) alone can be aptly classified as broad‐based and intense, their importance has further encouraged extensive development of variations on these themes (i.e., their composition and reactivity profiles). Reagents ( 1–3 ) have been found to be unexpectedly compatible with certain electrophilic additives at low temperatures, which substantially alter their reactivity. Rather than forming ( 2 ) from 2 equivalents of the same RLi, different organolithiums can be utilized to give R T R R CuLi, ( 4 ), conserving potentially valuable RLi. This scenario raises the question of controlling the selectivity of transfer of the desired ligand R T rather than the anticipated residual (or “dummy”) group R R from copper to electrophilic carbon. Fortunately, many solutions to this problem now exist. Admixture of 2RLi (or R T Li + R R Li) with copper(I) cyanide proceeds beyond the stage of ( 3 ) to ultimately arrive at copper(I) dianionic complexes 5 , the so‐called “higher‐order” cyanocuprates. Undoubtedly it is the cyano ligand, with its π‐acidic nature, which enables copper to accept a third negatively charged ligand. Although reagents ( 5 ) do not yet share in all of the benefits offered by time in comparison with their lower‐order counterparts, they nicely complement prior art. Moreover, as with species ( 1–4 ), they continue to evolve, providing the synthetic community with alternatives for highly selective and efficient means of making key carbon–carbon bonds.

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Bridged-ring steroids. II. The synthesis of bridged steroids with a bicyclo[2.2.1]heptane ring A system

Cited by 14 publications

References 18 publications

Antitumor Profile of Carbon-Bridged Steroids (CBS) and Triterpenoids

Antitumor Profile of Carbon-Bridged Steroids (CBS) and Triterpenoids

Bridged-ring steroids. V. The total synthesis of 1,4-methano steroids by a modified Torgov sequence

Organocopper Reagents: Substitution, Conjugate Addition, Carbo/Metallocupration, and Other Reactions

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