62563-07-9Relevant articles and documents
Chemoselective Oxidation of Equatorial Alcohols with N-Ligated λ3-Iodanes
Mikhael, Myriam,Adler, Sophia A.,Wengryniuk, Sarah E.
supporting information, p. 5889 - 5893 (2019/08/26)
The site-selective and chemoselective functionalization of alcohols in complex polyols remains a formidable synthetic challenge. Whereas significant advancements have been made in selective derivatization at the oxygen center, chemoselective oxidation to the corresponding carbonyls is less developed. In cyclic systems, whereas the selective oxidation of axial alcohols is well known, a complementary equatorial selective process has not yet been reported. Herein we report the utility of nitrogen-ligated (bis)cationic λ3-iodanes (N-HVIs) for alcohol oxidation and their unprecedented levels of selectivity for the oxidation of equatorial over axial alcohols. The conditions are mild, and the simple pyridine-ligated reagent (Py-HVI) is readily synthesized from commercial PhI(OAc)2 and can be either isolated or generated in situ. Conformational selectivity is demonstrated in both flexible 1,2-substituted cyclohexanols and rigid polyol scaffolds, providing chemists with a novel tool for chemoselective oxidation.
Synthesis method of 5-fluoro-2-(1-bromocyclopropyl) pyridine
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Paragraph 0016; 0023; 0027; 0034; 0038; 0045, (2019/08/01)
The invention relates to a synthesis method of 5-fluoro-2-(1-bromocyclopropyl) pyridine. 1,4-butyrolactone, ethyl 4-bromobutyrate and 5-fluoro-2-mercaptopyridine are used as raw materials to prepare 5-fluoro-2-(1-bromocyclopropyl) pyridine through eleven steps of reaction. A synthetic route of the 5-fluoro-2-(1-bromocyclopropyl) pyridine is as follows: (as described in the specification). The invention has the advantages that the synthesis method of 5-fluoro-2-(1-bromocyclopropyl) pyridine improves the yield and provides an efficient synthesis method for the synthesis of the compound.
(Poly)cationic λ3-Iodane-Mediated Oxidative Ring Expansion of Secondary Alcohols
Walters, Jennifer C.,Tierno, Anthony F.,Dubin, Aimee H.,Wengryniuk, Sarah E.
supporting information, p. 1460 - 1464 (2018/04/06)
Herein, a simplified approach to the synthesis of medium-ring ethers through the electrophilic activation of secondary alcohols with (poly)cationic λ3-iodanes (N-HVIs) is reported. Excellent levels of selectivity are achieved for C–O bond migration over established α-elimination pathways, enabled by the unique reactivity of a novel 2-OMe-pyridine-ligated N-HVI. The resulting hexafluoroisopropanol (HFIP) acetals are readily derivatized with a range of nucleophiles, providing a versatile functional handle for subsequent manipulations. The utility of this methodology for late-stage natural product derivatization was also demonstrated, providing a new tool for diversity-oriented synthesis and complexity-to-diversity (CTD) efforts. Preliminary mechanistic investigations reveal a strong effect of alcohol conformation on the reactive pathway, thus providing a predictive power in the application of this approach to complex molecule synthesis.
Mechanistic Studies on the Organocatalytic α-Chlorination of Aldehydes: The Role and Nature of Off-Cycle Intermediates
Ponath, Sebastian,Menger, Martina,Grothues, Lydia,Weber, Manuela,Lentz, Dieter,Strohmann, Carsten,Christmann, Mathias
supporting information, p. 11683 - 11687 (2018/09/10)
Herein we report the isolation and characterization of aminal intermediates in the organocatalytic α-chlorination of aldehydes. These species are stable covalent ternary adducts of the substrate, the catalyst and the chlorinating reagent. NMR-assisted kinetic studies and isotopic labeling experiments with the isolated intermediate did not support its involvement in downstream stereoselective processes as proposed by Blackmond. By tuning the reactivity of the chlorinating reagent, we were able to suppress the accumulation of rate-limiting off-cycle intermediates. As a result, an efficient and highly enantioselective catalytic system with a broad functional group tolerance was developed.
Total synthesis and structural revision of the alkaloid IncargranineB
Brown, Patrick D.,Willis, Anthony C.,Sherburn, Michael S.,Lawrence, Andrew L.
supporting information, p. 13273 - 13275 (2014/01/06)
Seeing double: Consideration of the biosynthetic origins of incargranineB, which was originally assigned an unprecedented indolo[1.7]naphthyridine structure, led to the proposal of a dipyrroloquinoline framework as a more biosynthetically feasible structure (see scheme; Piv=pivaloyl). This hypothesis was validated by a short biomimetic synthesis of incargranineB.
Enantioselective aldehyde α-nitroalkylation via oxidative organocatalysis
Wilson, Jonathan E.,Casarez, Anthony D.,MacMillan, David W. C.
supporting information; body text, p. 11332 - 11334 (2011/03/21)
(Chemical Equation Presented) The first enantioselective organocatalytic α-nitroalkylation of aldehydes has been accomplished. The aforementioned process involves the oxidative coupling of an enamine intermediate, generated transiently via condensation of an amine catalyst with an aldehyde, with a silyl nitronate to produce a β-nitroaldehyde. Two methods, one that furnishes the syn β-nitroaldehyde and a second that provides access to the anti isomer, have been developed. Data are presented to support a hypothesis that explains this phenomenon in terms of a silyl group-controlled change in mechanism. Finally, a three-step procedure for the synthesis of both syn- and anti-α,β-disubstituted β-amino acids is presented.
A synthesis of (±)-stemoamide using the intramolecular propargylic Barbier reaction
Bates, Roderick W.,Sridhar
experimental part, p. 1979 - 1981 (2010/06/17)
A diastereoselective synthesis of the alkaloid stemoamide has been achieved using the intramolecular propargylic Barbier reaction to construct the seven-membered ring. Georg Thieme Verlag Stuttgart.
A novel palladium-catalyzed arylation - dehydroaromatization reaction: Synthesis of 7-aryltetralones
Varseev, Georgy N.,Maier, Martin E.
, p. 3881 - 3884 (2007/10/03)
(Chemical Equation Presented) A new one-pot room-temperature palladium-catalyzed synthesis of 7-aryltetralones was discovered. This tandem process includes a palladium-catalyzed γ-selective arylation of the enone 4 followed by a dehydrogenation-aromatization of the initial cross-coupling product.
Asymmetric synthesis and structural assignment of (-)-α-conhydrine
Enders, Dieter,Nolte, Bert,Raabe, Gerhard,Runsink, Jan
, p. 285 - 291 (2007/10/03)
The first asymmetric synthesis of the conium alkaloid (-)-α-conhydrine is reported. Starting from a protected glycol aldehyde hydrazone as chiral precusor, a short route based on our α-alkylation/1,2-addition methodology has been developed. After cleavage of the auxiliary and simultaneous deprotection, the concluding ring closure is accomplished under reductive amination conditions. The title compound is obtained in moderate overall yield and in excellent diastereo- and enantiomeric excess (d.e., e.e. >96%). Single-crystal X-ray crystallography as well as 1H NMR NOE experiments confirm the expected relative and absolute (2R,7S)-configuration of the product.
SYNTHESES OF PROSTAGLANDIN AND LEUKOTRIENE C7 SYNTHONS THROUGH COMMON INTERMEDIATE COMPOUNDS
Bobrova, N. I.,Belosludtsev, Yu. Yu.,Pivnitskii, K. K.
, p. 1873 - 1878 (2007/10/02)
A method is proposed for the production of the C7-synthons used in the synthesis of eicosanoids (the methyl esters of 7-hydroxy-5Z-heptenoic and 6-formyl-5,6-trans-epoxyhexanoic acids) by a common scheme from readily obtainable tetrahydrofuran and propargyl alcohol.
