Total syntheses of optically active 19-nor steroids. (+)-Estr-4-ene-3,17-dione and (+)-13.beta.-ethylgon-4-ene-3,17-dione

Ra, Micheli; Zg, Hajos; Cohen, Noal; Dr, Parrish; La, Portland; W, Sciamanna; Ma, Scott; Pa, Wehrli

doi:10.1021/jo00894a003

Cited by 192 publications

(68 citation statements)

References 2 publications

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“…57 Recrystallization from n-hexane gave pure extracts were dried over anhydrous Na2SO4. Distillation gave pure 1-methylcyclopentene (6.79 g, 34.8%) at 71°C: 1 H NMR (300 MHz, CDCl 3) δ 1.70-1.75 (m, 3 H, CH3), 1.78-1.95 (m, 2 H, CH2 at C-4), 2.16-2.35 (m, 4 H, CH 2 at C-3 and C-5), 5.27-5.34 (m, 1 H, olefinic hydrogen).…”

Section: Methodsmentioning

confidence: 99%

Intramolecular Aldol Condensations: Rate and Equilibrium Constants

and

Guo

1996

J. Am. Chem. Soc.

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Rate and equilibrium constants have been determined for both the aldol addition and the elimination steps in the intramolecular condensation reactions of 2,5-hexanedione, 2,6-heptanedione, 1-phenyl-1,5-hexanedione, and 5-oxohexanal. The overall thermodynamics are similar for cyclization of 2,5-hexanedione and 2,6-heptanedione; conversion of 2,5-hexanedione to the corresponding enone is actually more favorable, but the cyclization of 2,5-hexanedione is 2400 times slower than that of 2,6-heptanedione. As expected on the basis of intermolecular analogs, the addition step is less favorable and slower for 1-phenyl-1,5-hexanedione, and the addition step for 5-oxohexanal is more favorable though similar in rate to that for heptanedione. Detailed analysis of the kinetics and equilibrium for all of these compounds, as well as 2-(2-oxopropyl)benzaldehyde, in terms of Marcus theory, leads to the same intrinsic barriers for the intramolecular reactions as were seen previously for the intermolecular reactions. This means that rate constants for intramolecular aldol reactions should be predictable from the energetics of the reactions and that the effective molarity can be calculated. Methods for estimating thermodynamic quantities for reactants and products of these reactions have been examined.

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Section: Methodsmentioning

confidence: 99%

Intramolecular Aldol Condensations: Rate and Equilibrium Constants

and

Guo

1996

J. Am. Chem. Soc.

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“…The isolated trans-hydrindane was carried forward through a series of Michael additions and annulations to yield the desired 19-nor-steroid systems for study. cold ethanol selectively reduced the more sterically free ketone to 4, which was then protected as the tert-butyl ether 5 through acid catalyzed reaction with isobutylene [16]. Upon reduction of 5 with mild reduction conditions for palladium catalyzed hydrogenation, it was found that the cis-hydrindane (cis-6) was formed in preference to the trans isomer (trans-6).…”

Section: Hajos-parrish Dionementioning

confidence: 99%

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

Eddy

Ichalkaranje

2016

Molecules

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Abstract:The bicyclo[4.3.0]nonane scaffold, commonly known as a hydrindane, is a common structural motif found in many terpenoid structures and one that remains a challenge for synthetic chemists to elaborate with appropriate regio-and stereo-selectivity. Over the course of the study of terpene natural products, the elaboration of the hydrindane structure has seen progress on the utilization of both old and newer methods to achieve the desired outcomes. This review seeks to serve as a general overview of these methods, and detail specific examples.

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“…After the NMR solution had been kept at 20Ϫ25°C for 0.5 h, the signals of a second isomer appeared (the ratio of the two isomers was determined by integration of the N-methyl signals in their 1 H NMR spectra; ratio major isomer/minor isomer ϭ 9:1). 1 Bis(azine) RED-13: Hydrazone 6 (0.44 g, 1.56 mmol) and heptane-2,6-dione [24] (12, 0.10 g, 0.78 mmol) yielded RED-13 (0.36 g, 70%), yellow powder with m.p. 124Ϫ125°C.…”

Section: 4ј-bis(dimethylamino)benzophenone Hydrazone (Michler's Ketmentioning

confidence: 99%

Electrochromics by Intramolecular Redox Switching of Single Bonds

et al. 2002

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Compounds of the general structure presented in Scheme 1 are proposed as electrochromic systems (ESs) in which reversible electron transfer is associated with breaking or forming of single bonds. In contrast to classical ESs, both redox states represent closed-shell systems. Whereas type OL/CS (Open form − Long-wavelength absorption/Closed form − Short-wavelength absorption) has already been demonstrated, this paper presents examples of the OS/CL type, in which the long-wavelength absorption is displayed by the ring-closed form. Bis(azines) RED-8, RED-13, RED-16, and RED-17, as well as the bis(amines) RED-22, RED-23, and RED-24 were prepared and characterized by their cyclic vol-

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Total syntheses of optically active 19-nor steroids. (+)-Estr-4-ene-3,17-dione and (+)-13.beta.-ethylgon-4-ene-3,17-dione

Cited by 192 publications

References 2 publications

Intramolecular Aldol Condensations: Rate and Equilibrium Constants

Intramolecular Aldol Condensations: Rate and Equilibrium Constants

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

Electrochromics by Intramolecular Redox Switching of Single Bonds

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