查看更多>>摘要：Abstract Cascade reactions of 1,3‐diarylpropane‐1,3‐dione or unsaturated ketones with arylsulfonyl hydrazide have been achieved in the presence of iodine source. Fully substituted C4‐sulfenylated pyrazoles were synthesized via the tandem pyrazole annulation and C(sp2)?H sulfenylation. This approach is efficient and practical. The starting materials are readily available, while also providing a useful strategy for the construction of different arylthio‐substituted pyrazole skeletons.
查看更多>>摘要：Abstract We describe the synthesis of seven C2‐alkylcarbazoles via a sequence of Buchwald–Hartwig coupling of arylamines with aryl halides followed by oxidative cyclization of the resulting diarylamines. Methyl groups at the positions 4 and 5 were introduced by taking advantage of the ortho‐directed palladation of meta‐pivaloyloxy‐substituted diarylamines and subsequent conversion of the pivaloyloxy to methyl groups through Stille coupling of intermediate triflates. The obtained ethyl‐ and dimethylcarbazoles served as analytical standards for their identification in petroleum samples and source rocks.
Izabela A. SantosPedro P. CastroHélio F. Dos SantosGiovanni W. Amarante...
7页
查看更多>>摘要：Abstract The full mechanism of the asymmetric α‐thiolation of azlactones catalyzed by a cinchona alkaloid‐derived squaramide was carefully investigated through theoretical calculations. The results revealed that the reaction proceeds in two sequential steps. First, the azlactone α‐deprotonation by the catalyst tertiary amine group (which for the major product is the rate‐limiting step) affords a chiral molecular aggregate containing the azlactone enolate. Next, three proposals were evaluated concerning the enantiodetermining step (carbon‐sulfur bond formation). It was possible to exclude the azlactone enol as a key intermediate. The most viable pathway consists of a Münchnone‐type activation mode, which associated with secondary hydrogen bonding interactions between the catalyst and the thiolating reagent (bifunctional catalysis), is responsible for the asymmetric induction process. Thus, by using two different reaction conditions, the theoretical enantiomeric excesses were computed and compared with literature data, presenting a good correlation with the reported experimental values.
查看更多>>摘要：Abstract 2‐(2‐Bromoaryl)indoles react with aryl isocyanates by microwave irradiation in the presence of catalytic CuI along with a base to afford 5‐arylindolo[1,2‐c]quinazolin‐6(5H)‐ones. The reaction is compatible with 2‐(2‐bromoaryl)indoles bearing straight and branched alkyl chains at position 3 of indole moiety. Both electron‐donating and ‐withdrawing substituents on bromophenyl and indole moieties are well tolerated. The reaction proceeds through an initial nucleophilic addition of 2‐(2‐bromoaryl)indoles to aryl isocyanates. This is followed by an intramolecular C?N bond formation by an addition‐elimination nucleophilic aromatic substitution via Meisenheimer complexes and a copper‐catalyzed Ullmann‐type coupling.
查看更多>>摘要：Abstract The previous synthetic strategy for the preparation of non‐fluorescent fluoresceins was mostly limited to the double addition of simple alkenes and alkynes. We report the one‐step masking of Pittsburgh Green to its mono‐alkylated or esterified compounds. Unlike previous syntheses, this strategy tolerates a broader range of functional groups as masking groups. We also demonstrate the advantage of mono‐alkylation over di‐alkylation for metal detection.
查看更多>>摘要：Abstract Hydroxamates derived from 3‐sulfolene‐3‐carboxylic acid can be involved in intra‐ and intermolecular rhodium(III)‐catalyzed heteroannulations with alkynes proceeding through C(sp2)?H bond activation. These transformations allow for a straightforward access to diversely substituted pyridones, and to pyridines fused to a sulfolene ring after functional group transformations. Subsequent cheletropic elimination of sulfur dioxide can be achieved under microwave irradiation to generate pyridine ortho‐quinodimethanes. These results demonstrate that the scope of rhodium(III)‐catalyzed C(sp2)?H functionalizations can be extended to sulfolenes, a yet unexplored class of alkenes in these latter transformations, thereby affording access to valuable classes of heterocyclic products.
Bi Bali Judica?l TraAbollé AbolléVincent CoeffardFran?ois‐Xavier Felpin...
10页
查看更多>>摘要：Abstract Described herein is a divergent continuous‐flow approach for the biomimetic oxidative cyclization of reticuline‐type alkaloids to aporphine and morphinandienone natural products using hypervalent iodine(III) reagents. The method was based on the detailed knowledge of the reaction mechanisms in order to develop robust reaction conditions toward the selective synthesis of either aporphine or morphinandienone natural products. In this frame, we exploited the ability of HFIP to stabilize radical cation intermediates and to activate hypervalent iodine(III) oxidants for the flow synthesis of aporphine natural products such as glaucine, rogersine and nantenine. On the other hand, we established that PhI(OAc)(OTf), prepared by action of TMSOTf on PhI(OAc)2, was a powerful oxidant for the synthesis of morphinandienone natural products such as sebiferine and amurine.
Alexey P. KrinochkinYaroslav K. ShtaitzAluru RammohanIlya I. Butorin...
7页
查看更多>>摘要：Abstract An operationally facile and high yielding one‐pot protocol has been developed for the preparation of pyridines appended with pyrazole via NH linker. This protocol includes SNipso/aza‐Diels‐Alder reactions in up to 54?% yields starting from 1,2,4‐triazine precursors. All the synthesized compounds have been evaluated for their in silico activity against JAK1, SYK, and FAK1 kinases. The most promising compound was tested in?vitro using A‐172, Hs578T, and HepG2 cancer cell lines and exhibited considerable cytotoxicity with IC50 values <50?μM in A‐172 and HepG2?cell lines. Anticancer in?vitro activity correlates well with the predicted in silico data.
Yoarhy A. Amador‐SánchezPedro López‐MendozaMarco V. MijangosLuis D. Miranda...
5页
查看更多>>摘要：Abstract An efficient protocol for the synthesis of poly‐functionalized 1,2,3,6‐tetrahydro‐4H‐pyrido[1,2‐b]isoquinolin‐4‐ones is described. First, propargyl‐containing Ugi adducts were transformed to polysubstituted dihydroisoquinolines by an intramolecular Au‐catalyzed alkyne hydro‐arylation, followed by the alkene isomerization process. Then, these pivotal intermediates were engaged in a xanthate‐based oxidative radical cascade addition/cyclization process with a suitable alkene.
NSTL
Wiley