Tris(3,6-dioxaheptyl)amine: A superior complexing agent for dissolving metal reactions

Bose, Ajay K.; Mangiaracina, Pietro

doi:10.1016/s0040-4039(00)95452-2

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…Subsequent hydrogenation afforded 17β-methyl compound 14 [11] in 97 % yield as a single diastereomer (by GLC), which was submitted to PCC oxidation [12] (94 % yield) to give ketone 13. [11] Huang-Minlon reduction gave hydrocarbon 2 [13] in 85 % yield. A-ring-contracted steroids, specifically A-nor-steranes, were reported to be constituents of sedimentary hydrocarbon mixtures.…”

Section: Resultsmentioning

confidence: 99%

“…[20] Application of TTN-mediated ring contraction gave a material containing carboxylic acid 17, which was not purified, but directly submitted to LiAlH 4 reduction. Alcohol 19 was obtained in 57 % yield (from ketone 18) and unexpectedly as a single diastereomer (by 13 C NMR spectroscopy and GLC). droxymethyl group at position 2 of the A-nor-ring, was established by 2D NMR spectroscopy: In the HMBC spectrum, the 2-CH 2 protons showed a 3 J( 1 H, 13 C) correlation to C-1 and C-3, which were both identified to be methylene groups by a DEPT135 experiment.…”

Section: Resultsmentioning

confidence: 99%

“…Alcohol 19 was obtained in 57 % yield (from ketone 18) and unexpectedly as a single diastereomer (by 13 C NMR spectroscopy and GLC). droxymethyl group at position 2 of the A-nor-ring, was established by 2D NMR spectroscopy: In the HMBC spectrum, the 2-CH 2 protons showed a 3 J( 1 H, 13 C) correlation to C-1 and C-3, which were both identified to be methylene groups by a DEPT135 experiment. Our synthetic plan was then to eliminate the hydroxy group after activation and then hydrogenate the corresponding exocyclic olefin.…”

Section: Resultsmentioning

confidence: 99%

“…TLC was performed on Merck SiO 2 F 254 plates on aluminum sheets. 1 H and 13 C NMR spectra were recorded with a Bruker Avance DRX 500 spectrometer. Multiplicities of 13 C signals were determined with DEPT experiments.…”

Section: Methodsmentioning

confidence: 99%

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Androstanes with Modified Carbon Skeletons

et al. 2011

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Four sterane hydrocarbons were prepared for comparison with fossil organic biomarkers in geological samples from Oman. 17β-Methylestrane was prepared in six steps (36 % overall yield) from estrone methyl ether. Key steps of this sequence were a Wittig olefination and Birch reduction of the A-ring. 17β-Methylandrostane was obtained in four steps (85 % overall yield) from trans-androsterone by four functional group interconverting reactions, including a Wittig ole-

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Androstanes with Modified Carbon Skeletons

et al. 2011

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“…The halosteroid (43) was dehalogenated with Na-K alloy, tertbutyl alcohol, and TDA-1 in THF to give the desired product in 81% (X = Cl) and 80% (X = Br) yields (eq 17). 23 18-Crown-6 gave inferior results: 59% (X = Cl) and 57% (X = Br) yields. (17) Olefinations.…”

Section: Alkylations and Arylationsmentioning

confidence: 95%

Tris[2-(2-methoxyethoxy)ethyl]amine

Tanoury

Senanayake

2003

Encyclopedia of Reagents for Organic Synthesis

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The Barton‐McCombie Reaction

2012

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Deoxygenations of alcohols, i.e., processes that replace a hydroxyl group with hydrogen at a saturated carbon, find applications in both total synthesis and the systematic modifications of natural products. They may also be employed to introduce deuterium or tritium in a site‐specific manner. Reductive methods that involve ionic or highly polarized reagents or intermediates can be limited in their applicability: for example, competing reaction pathways including cationic rearrangements and anionic eliminations may be encountered in sterically hindered systems with substrates bearing heteroatoms close to the center undergoing reduction. As evidenced by developments over the last few decades, methods that involve the generation and direct quenching via hydrogen atom abstraction of the derived, carbon‐centered radical typically show the greatest tolerance for the presence of other functional groups and for variations in both the steric acid and the electronic environment in the vicinity of the center undergoing deoxygenation. Derivatization of the hydroxyl is a prerequisite, the determinant factors for efficient formation of the deoxygenated product lies in the ability of the combination of the substrate and reagents to induce homolysis of the C‐O bond coupled with the induction of homolysis to rapidly reduce a free radical by hydrogen donation, thereby propagating an efficient chain process. A high‐yielding way to realize this sequence was first described by Barton McCombie using the free‐radical chain reaction of O ‐thioacyl derivatives of secondary alcohols with tri‐ n ‐butylstannane. This chapter provides a detailed description and comparison of the combinations of substrates and reagents that will bring about these processes and provides a summary and evaluation of alternative deoxygenation methods. Mechanistic and stereochemical issues set out the scope and limitations of these processes with respect to both the thioacylation and reduction steps and exemplify some applications to both total synthesis and the modification of natural products.

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Tris(3,6-dioxaheptyl)amine: A superior complexing agent for dissolving metal reactions

Cited by 13 publications

References 10 publications

Androstanes with Modified Carbon Skeletons

Androstanes with Modified Carbon Skeletons

Tris[2-(2-methoxyethoxy)ethyl]amine

The Barton‐McCombie Reaction

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