193634-77-4Relevant academic research and scientific papers
Exploratory synthetic investigations related to 12a-deoxypillaromycinone
Wang, Lan,Meegalla, Sanath K.,Fang, Cheng-Lin,Taylor, Nicholas,Rodrigo, Russell
, p. 728 - 738 (2002)
Furfural is converted to suitably substituted AB synthon 21 for 12a-deoxypillaromycinone in 10 steps by a sequence involving the following key steps: intramolecular Diels-Alder reaction of a furan, 5-endo-trig cleavage of the oxabicyclo adducts 18, and catalytic hydrogenation of the double bond of a tetrasubstituted enone to produce 19. Enones 21a and 21b obtained by dehydrogenation of 19a and 19b, respectively, are then annulated with ethyl 2-methoxy-6-methylbenzoate in a four-step procedure to generate tetracyclic products 25 in 14 steps from furfural.
Concise stereoselective and stereodivergent syntheses of (±)-melicolones A and B
Wang, Zhipeng,Martin, Stephen F.
, (2021/11/26)
The first total syntheses of the epimeric (±)-melicolones A and B, which are bioactive constituents isolated as racemates from the leaves of Melicope ptelefolia, were achieved in 12.3% combined overall yield. The divergent approach to these unusual natural products is remarkably concise and required a longest linear sequence of only nine steps (11 total steps) from commercially available starting materials. The significant synthetic challenge posed by the unique and densely functionalized polycyclic framework characteristic of the melicolones was addressed by a novel and highly regioselective (16:1) and diastereoselective (15:1) dipolar cycloaddition to deliver the oxabicycloheptane core. This pivotal reaction featured an innovative combination of an unsaturated vinylogous ester dipolarophile with a carbonyl ylide that was generated by an unusual cyclization of the carbonyl oxygen atom of an aliphatic aldehyde with a rhodium carbenoid. Stereoselective prenylation of the ketone enolate derived from this bicyclic core gave an intermediate that was processed via a one-pot O-demethylation cycloaldolization sequence to give the penultimate intermediate. The synthesis was completed by a bioinspired tandem epoxidation of the prenyl substituent followed by a regioselective, acid-catalyzed cyclization to deliver (±)-melicolones A and B. This approach may be applicable to the syntheses of other melicolones having a tetracyclic core.
Potassium Base-Catalyzed Michael Additions of Allylic Alcohols to α,β-Unsaturated Amides: Scope and Mechanistic Insights
Kurouchi, Hiroaki,Sai, Masahiro
supporting information, p. 3585 - 3591 (2021/06/27)
We report herein the first KHMDS-catalyzed Michael additions of allylic alcohols to α,β-unsaturated amides through allylic isomerization. The reaction proceeds smoothly in the presence of only 5 mol% of KHMDS to afford a variety of 1,5-ketoamides in high yields. Mechanistic investigations, including experimental and computational studies, reveal that the KHMDS-catalyzed in-situ generation of the enolate from the allylic alcohol through a tunneling-assisted 1,2-hydride shift is the key to the success of this transformation. (Figure presented.).
Ionic liquids, microwave irradiation, and the synthesis of aryl Weinreb amides
Otaibi, Ahmed Al,McCluskey, Adam
, p. 519 - 525 (2017/12/15)
Abstract: The Heck coupling of aryl halides and N-methoxy-N-methylacrylamide was investigated in the room-temperature ionic liquids [BMIM][PF6], [BMIM][Br], [BMIM][BF4], [BMIM][OH], [BMIM][HCOO], EAN, PAN, and ETAN. Excellent yields of the expected N-methoxy-N-methylcinnamamides (ca 90%) and purity (>?96%) were afforded on simple diethyl ether extraction from [BMIM][PF6] and [BMIM][OH]. The described procedure was highly substrate tolerant with methyl, methoxy, fluoro, trifluoromethyl, ester, cyano, hydroxy, naphthyl, and quinolone moieties well tolerated. Poor yields or no reactions were observed with –NH2 and –NO2 moieties. The use of microwave irradiation reduced reaction times from 3?h (thermal) to 5–15?min with no substantive effect on reaction outcome. Graphical abstract: [Figure not available: see fulltext.].
Convergent synthesis of 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines by substitution reactions of Weinreb amide group of tetrahydropyrimidines
Nishimura, Yoshio,Kubo, Takanori,Okamoto, Yasuko,Cho, Hidetsura
supporting information, p. 4492 - 4495 (2016/09/14)
A method of convergent and stepwise synthesis of novel 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines using the Weinreb amide group is developed. The cyclization of 4-dimethylamino-1,3-diaza-1,3-butadiene having N-protecting groups (Boc) with N-methoxy-N-methylacrylamide gives 6-unsubstituted 4-dimethylamino-2-phenyltetrahydropyrimidine, which is a synthetic intermediate for 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines. The transformation of the Weinreb amide group to an acyl group via substitution reaction using organolithium reagents, following the elimination of a dimethylamino group using MeI proceeds smoothly, affording 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines in good overall yield. The N-protecting group can be easily removed to obtain N-unsubstituted dihydropyrimidines as a mixture of tautomers, and their tautomeric behaviors were analyzed by1H NMR spectroscopy.
Determination of the absolute configuration of phosphinic analogues of glutamate
Commare, Bruno,Rigault, Delphine,Lemasson, Isabelle A.,Deschamps, Patrick,Tomas, Alain,Roussel, Pascal,Brabet, Isabelle,Goudet, Cyril,Pin, Jean-Philippe,Leroux, Frdric R.,Colobert, Franoise,Acher, Francine C.
supporting information, p. 1106 - 1112 (2015/03/03)
A series of phosphinic glutamate derivatives (e.g.LSP1-2111) have been proven to be potent agonists of metabotropic glutamate (mGlu) receptors and shown promising in vivo activity. However, so far all were synthesized and tested as a mixture of two diaste
Highly efficient and environmentally benign preparation of Weinreb amides in the biphasic system 2-MeTHF/water
Pace, Vittorio,Castoldi, Laura,Alcantara, Andres R.,Holzer, Wolfgang
, p. 10158 - 10162 (2013/09/02)
A straightforward chromatography-free preparation of Weinreb amides starting from acid halides has been achieved in the biphasic medium 2-MeTHF/water. Analytically pure compounds were isolated in excellent yields simply after removal of 2-MeTHF, which abs
Synthesis of 3-pyrroline via domino Heck-aza-Michael reaction
Wu, Pan,Liu, Hui,Tong, Xiaofeng
supporting information; experimental part, p. 4673 - 4675 (2012/09/05)
This Letter describes the Pd(0)-catalyzed domino Heck-aza-Michael reaction between (Z)-N-(3-iodoallyl)-tosylamide and acrylic ester. The reaction provides a facile access to an important class of substituted 3-pyrroline.
Ruthenium- and rhodium-catalyzed cross-coupling reaction of acrylamides with alkenes: Efficient access to (Z,E)-dienamides
Zhang, Jian,Loh, Teck-Peng
supporting information, p. 11232 - 11234 (2013/01/15)
Ruthenium- and rhodium-catalyzed direct oxidative cross-coupling reactions of acrylamides with alkenes were developed. These methods provide an efficient route for the synthesis of (Z,E)-dienamides in excellent yields with good stereoselectivity. The catalytic systems allowed oxidative olefination of a wide range of alkenes bearing different functional groups, such as CO2R, COMe, SO2Ph, aryl, CONHBn, CN, PO(OEt)2, as well as Weinreb amide.
Cross-metathesis of allyl halides with olefins bearing amide and ester groups
Yun, Jeong In,Kim, Hyoung Rae,Kim, Sang Kyum,Kim, Deukjoon,Lee, Jongkook
experimental part, p. 1177 - 1184 (2012/02/16)
An investigation was conducted to determine whether the cross-metathesis (CM) of allyl halides tolerates amide groups. The results show that the ruthenium-based complexes I-III serve as poor catalysts for the CM of allyl halides with olefins that contain an N,N-dimethylamide group. In contrast, the Grubbs-Hoveyda-Blechert second generation catalyst (III) efficiently promotes these processes with olefins bearing a Weinreb amide group. Lastly, a reinvestigation of the ester group tolerance of the allyl halide CM with unsaturated esters demonstrated that III serves as an efficient catalyst for these reactions.
