2681-55-2Relevant articles and documents
Ni-catalyzed direct alcoholysis of N-acylpyrrole-type tertiary amides under mild conditions
Chen, Hang,Chen, Dong-Huang,Huang, Pei-Qiang
, p. 370 - 376 (2020/03/03)
N-Acylpyrrole-type amides are a class of versatile building blocks in asymmetric synthesis. We report that by employing Ni(COD)2/2,2′-bipyridine (5 mol%) catalytic system, the direct, catalytic alcoholysis of N-acylpyrrole-type aromatic and aliphatic amides with both primary and secondary alcohols can be achieved efficiently under very mild conditions (rt, 1 h) even at gram scale. By increasing the catalyst loading to 10 mol%, prolonging reaction time (18 h), and/or elevating reaction temperature to 50 °C/80 °C, the reaction could be extended to both complex and hindered N-acylpyrroles as well as to N-acylpyrazoles, Nacylindoles, and to other (functionalized) primary and secondary alcohols. In all cases, only 1.5 equiv. of alcohol were used. The value of the method has been demonstrated by the racemization-free, catalytic alcoholysis of chiral amides yielded from other asymmetric methodologies.
Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations
Svec, Riley L.,Hergenrother, Paul J.
supporting information, p. 1857 - 1862 (2019/12/27)
Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
Method for synthesizing methyl 3-oxo-4-androstene-17beta-carboxylate
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Paragraph 0013; 0036; 0037; 0038; 0045; 0046; 0047, (2019/03/29)
The invention discloses a method for synthesizing methyl 3-oxo-4-androstene-17beta-carboxylate. The method comprises the following steps: (a) performing etherification protection on 3-site keto groupwith sterol fermentation broth androst-4-allyl-3,17-diketone as a starting material to obtain a compound shown by the formula 2 as shown in the specification; (b) performing Witt reaction on 3-site keto of the compound shown by the formula 2, and performing hydrolysis rearrangement to obtain a compound shown by the formula 3 as shown in the specification; and (c) performing esterification on the compound shown by the formula 3, and then collecting methyl 3-oxo-4-androstene-17beta-carboxylate shown by the formula 1 as shown in the specification from reaction products. The method disclosed in the invention has the advantages that raw material sources are stable, the pollution is less, the environmental protection is achieved and the price is low, therefore, the synthesis method is low in cost, easy, convenient and fast in process and more environmentally-friendly. The response equation is shown in the specification.
Protection of COOH and OH groups in acid, base and salt free reactions
Zhu, Xiaotao,Qian, Bo,Wei, Rongbiao,Huang, Jian-Dong,Bao, Hongli
supporting information, p. 1444 - 1447 (2018/04/12)
We report an iron-catalyzed general functional group protection method with inexpensive reagents. This environmentally benign process does not use acids or bases, and does not produce waste products. Further purification beyond filtration and evaporation is, in most cases, unnecessary. Free COOH and OH groups can be protected in a one-pot reaction.
Effective and mild method for converting 3β-hydroxysteroids to 3-keto steroids via DDQ/TEMPO
Zhang, Wu,Pan, Dan,Wu, Aiqun,Shen, Liqun
, p. 16 - 20 (2015/03/04)
A mild and efficient oxidation of 3β-hydroxysteroids to the corresponding 3-keto steroids can be carried out at room temperature, using DDQ in the presence of catalytic TEMPO. Oxidation of saturated 3β-hydroxysteroids gave the corresponding ketones in excellent yield. The 5-unsaturated 3β-hydroxysteroids are oxidized selectively to 4-en-3-one or 4,6-diene-3-one derivatives according to the amount of DDQ in reaction. This is a good method for the synthesis of 4,6-diene-3-one from the corresponding 3β-hydroxy-5-ene steroids. Meanwhile, configurations of the oxidation compounds 2a, 2b, 3b, 2c, 2f and 2g were identified by X-ray diffraction. A possible mechanism is presented and discussed.
The first synthesis of Krempene B
Shen, Li-Qun,Huang, Su-Yu,Tang, Yong,Lei, Fu-Hou
, p. 1398 - 1402 (2013/01/15)
The synthesis of Krempene B, which can be isolated from the marine soft coral Cladiella krempfi, is achieved in 23.9% overall yield from commercially available 3β-acetoxy-5-pregnen-20-one by 11 steps. Key transformations include the dienone-phenol rearrangement of steroids and Wittig reaction.
Design and diastereoselective synthesis of C-2,C-20-diaryl steroidal derivatives
Rey, Jullien,O'Riordan, Timothy J. C.,Hu, Haipeng,Snyder, James P.,White, Andrew J. P.,Barrett, Anthony G. M.
supporting information; experimental part, p. 3781 - 3794 (2012/10/08)
A novel and efficient synthetic strategy to access unique C-2 substituted steroid analogues 3 and 4 is described. The unusual C-2 aryl ether analogues 3 were shown to act as virtual antagonists of LRH-1 and were prepared as single diastereoisomers, employing a fifteen-step sequence from pregnenolone (9). The key steps include the stereoconvergent nucleophilic displacement of an epimeric mixture of 3-keto 2-bromo steroids, chemoselective carbonylation of an enol triflate and conversion of a thiopyridyl ester into an aryl ketone. The related C-2 benzyl analogues 4 were prepared in a similar manner. Starting from pregnenolone, a diastereoselective fifteen-step synthesis was developed to access novel C-2-substituted steroid analogues. A range of C-2 benzyl and aryl ether analogues were prepared to probe their efficacy as antagonists of the nuclear receptor LRH-1. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
The oxidation of 3-hydroxy-3-methyl-Δ4-steroids by chromium trioxide
Uyanik, Cavit,Hanson, James R.,Hitchcock, Peter B.
, p. 795 - 797 (2007/10/03)
Oxidation of the allylic tertiary alcohols of 3-hydroxy-3-methyl-Δ 4-steroids by chromium trioxide in sulfuric acid leads to C-C bond fission together with the formation of a 3-methylestra-1,3,5(10)-triene from a 19-nor steroid and a 3β,4β-epoxy-5β-hydroxy compound from an androstane; the structure of the hydroxy-epoxide was established by X-ray crystallography.
Anti-AIDS agents. Part 36: 17-carboxylated steroids as potential anti-HIV agents
Xia, Peng,Yang, Zheng-Yu,Xia, Yi,Zheng, Yun-Qing,Cosentino, L.Mark,Lee, Kuo-Hsiung
, p. 1907 - 1911 (2007/10/03)
In our search for novel anti-HIV agents, seven 17-carboxylated steroid derivatives were synthesized and evaluated as potential anti-HIV agents. Compound 13 exhibited potent anti-HIV activity in acutely infected H9 lymphocytes with EC50 and therapeutic index values of 0.8 μM and 300, respectively.
Steroidal Aphidicolin Analogues Derived from Pregnenolone
Hanson, James R.,Yildirim, Kudret
, p. 2975 - 2991 (2007/10/03)
The converision of pregnenolone into the 3β,5α-, 3α,5α-, 4β,5α-, 3β,4α, 3α,4β- and 3α,4α-dihydroxy derivatives of 17β-hydroxymethyl-5α-androstane as steroidal analogues of the diterpenoid DNA polymerase α inhibitor, aphidicolin, is described.
