Asymmetric synthesis of 19-norsteroids

Pappo, Raphael; Garland, Robert B.; Jung, Changyoung; Nicholson, Robert T.

doi:10.1016/s0040-4039(01)96250-1

Cited by 15 publications

(3 citation statements)

References 7 publications

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“…spectrum of the latter was identical with that of the racemate synthesized by the method reported earlier [S]. The sign of optical rotation of the compound obtained also proved C3 hydroxy group to be in @-configuration, which is keeping with the chiroptical properties of another chiral prostaglandin synthone-namely ( -)-4B-hydroxy-2-(6'-methoxycarbonylhexyl)-cyclopent-2-en-l-one [9].…”

supporting

confidence: 82%

Intermediates of Prostanoid Synthesis. Stereospecific conversion of (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone into (+)‐1β‐methoxycarbonylmethyl‐2β,3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one

et al. 1987

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Starting from (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone (1), (+)‐1β‐methoxycarbonylmethyl‐2β, 3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one (7) was prepared within 4 steps. Subsequent cleavage of the latter gives (−)‐3β‐hydroxy‐1‐methoxy‐carbonylmethylcyclopent‐1‐en‐5‐one (8a). Hydroxylation of the lactone (1) was found to give (+)‐2β,3β,5β‐trihydroxycyclopentyl‐1β‐acetic acid γ‐lactone (2a) with cis‐oriented hydroxy groups in respect to the lactone ring. No formation of the trans‐isomer, as has been reported earlier [4], was observed.

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supporting

confidence: 82%

Intermediates of Prostanoid Synthesis. Stereospecific conversion of (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone into (+)‐1β‐methoxycarbonylmethyl‐2β,3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one

et al. 1987

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“…In a fruitful application of organoborane chemistry to steroid total synthesis, the (llS)-(-)-a-acetoxy diazo ketone 19a, upon reaction with tris[2-(3-methoxyphenyl) -1 -ethyl] bor ane, followed by oxidation of borate intermediates, yielded the 13/3-ACD-tricyclic ketol 20a in on enantiomeric excess of at least 95 % ,24a In a similar manner, the (llS)-a-chloro analog 19b gave rise to 20b in optically pure form.24h The seco intermediates 20 could be efficiently transformed24 into either 11substituted aromatic steroids or the important dienone 18b14b- 16,18 (obtained in 56% overall yield based on 19b).…”

Section: Cohenmentioning

confidence: 99%

“…In addition to the substantial asymmetric induction observed in their formation, the dienes 8 proved to be especially desirable intermediates with regard to introduction of the required CD-trans ring fusion stereochemistry, a classical problem encountered in many approaches to steroid total synthesis.1•22 Thus, it was observed that catalytic hydrogenation of the 14,15conjugated double bond in the derived 17ß alcohols 15a,b,d,e occurred almost exclusively from the a face of the molecules, giving the CD-trans-fused enol ethers 17 0,b,d,e 18 a, R = OH and HIM 18b ; R = 0 (21) This material could be isolated when 5a was reacted with 2-methylcyctopentane-l,3-dione in tert-butyl alcohol-water at 50 °C.20h An x-ray crystallographic analysis of (±)-10a (carried out by Dr. J. Blount) confirmed the intriguing, tricyclic, internally hydrated structure, i, which this compound possesses, in the solid state. Amiard, and V. Torelli, Bull.…”

Section: Cohenmentioning

confidence: 99%