17021-78-2Relevant articles and documents
Direct Synthesis of α-Amino Nitriles from Sulfonamides via Base-Mediated C-H Cyanation
Shi, Shasha,Yang, Xianyu,Tang, Man,Hu, Jiefeng,Loh, Teck-Peng
supporting information, p. 4018 - 4022 (2021/05/26)
Herein, we disclose a transition-metal-free reaction system that enables α-cyanation of sulfonamides through C-H bond cleavage for the preparation of α-amino nitriles, including difficult-to-access all-alkyl α-tertiary scaffolds. More than 50 substrate examples prove a wide functional group tolerance. Additionally, its synthetic practicality is highlighted by gram-scalability and the late-stage modification of natural compounds. Mechanistic experiments suggest that this process involves in situ formation of an imine intermediate via base-promoted elimination of HF.
Total Synthesis of (-)-C/D-cis-Dehydro-3-O-methyl-estradiols
Kaluza, Nora M.,Schollmeyer, Dieter,Nubbemeyer, Udo
supporting information, p. 357 - 366 (2016/02/12)
A convergent synthesis of (-)-dehydro-3-O-methyl-C/D-cis-estradiol started from stereochemically defined substituted optically active 3-(2-arylethyl)-γ-butyrolactones. Regioselective bromination of the anisyl moiety, reductive ring opening of the iodolactone, and protecting-group changes led to a Weinreb amide. This then underwent an intramolecular Grignard reaction closing the B-ring to give a tetralone with defined configuration. Introduction of C-11 through an allyl Grignard addition and subsequent ring-closing metathesis gave a tetrahydro phenanthrene derivative. Oxidation of the side-chain alcohol resulted in the key aldehyde group, and a final samarium-diiodide-mediated reductive D-ring annulation resulted in the generation of the target dehydro-C/D-cis-estradiol derivatives with high stereoselectivity. Structure elucidation was carried out using NOEDS (nuclear Overhauser enhanced differential spectroscopy) analysis on the one hand, and conversion into known 3-O-methyl-13β-estradiols by double-bond hydrogenation on the other. Further efforts to use this estradiol synthetic strategy to generate more complex steroidal natural products and pharmaceutically interesting compounds are in progress.
A simple and convenient synthesis of 2-methoxyestradiol from estrone
Prakasham,Shanker, Karuna,Negi, Arvind S.
scheme or table, p. 467 - 470 (2012/05/19)
A simple and straightforward synthesis of 2-methoxyestradiol have been achieved in nine synthetic steps with 21% of overall yield. Being a convenient process, it can be upscaled to industrial process.
Combined epimerisation and acylation: Meerwein-ponndorf-verley-oppenauer catalysts in action
Klomp, Dirk,Djanashvili, Kristina,Svennum, Nina Cianfanelli,Chantapariyavat, Nuttanun,Wong, Chung-Sing,Vilela, Filipe,Maschmeyer, Thomas,Peters, Joop A.,Hanefeld, Ulf
, p. 483 - 489 (2007/10/03)
A practical racemisation-epimerisation method for chiral secondary alcohols has been developed. Meerwein-Ponndorf-Verley-Oppenauer catalysts such as neodymium(III) isopropoxide are able to racemise these alcohols with retention of other stereocentres in the molecule. This is particularly useful for the recycling of the undesired products of kinetic resolutions of alcohols. By combination of such a racemisation with an acylation using isopropenyl or ethoxyvinyl esters as acyl donors, a fast straightforward recycling of starting materials may be achieved. The combined epimerisation and acylation process is demonstrated for the steroid estradiol methyl ether.
Transition metal-catalyzed intramolecular [4+2] cycloadditions: Mechanistic and synthetic investigations
Wender, Paul A.,Smith, Thomas E.
, p. 1255 - 1275 (2007/10/03)
The nickel-catalyzed intramolecular cycloaddition of dienes with unactivatable alkynes is found to proceed under mild conditions while the corresponding Diels-Alder cycloaddition of the same substrates either fails of occurs only under forcing conditions. The nickel-catalyzed cycloaddition is also shown to occur with retention of stereochemistry and is not significantly influenced by electronic effects. Finally, the catalyzed process is shown to be applicable to the synthesis of angularly substituted bicycles, including the CD ring systems of steroids and vitamin D.
