Six-membered ring systems: with O and/or S atoms

A large variety of publications involving O- and S-6-membered ring systems have appeared in 2017. The importance of these heterocyclic compounds is highlighted by the huge number of publications on the total synthesis of natural oxygen derivatives and of other communications dedicated to synthetic derivatives. Reviews on stereoselective organocatalytic synthesis of tetrahydropyrans (17EJO4666), of tetrahydropyrans and their application in total synthesis of natural products (17CSR1661), on the synthesis of the less thermodynamically stable 2,6-trans-tetrahydropyrans (17S4899), on enantioselective synthesis of polyfunctionalized pyran and chromene derivatives (17TA1462), and on enantioselective and racemic total synthesis of camptothecins, including the formation of their pyran-2-one ring (17SL1134), have appeared. Advances in the transition metal-catalyzed synthesis of pyran-2/4-ones (17TL263), N-heterocyclic carbene (NHC)-catalyzed achiral synthesis of pyran-2-one, coumarin and (thio)chromone derivatives (17OBC4731), on the synthesis and transformation of 2H-pyran-2-ones (17T2529) and 2-styrylchromones (17EJO3115) into other heterocyclic compounds, have been surveyed. The strategies to build up the tetrahydropyranyl core of brevisamide (17H(95)81) and the reactions of ketyl radicals, generated from carbonyl derivatives under transition-metal photoredox-catalyzed conditions, leading to isochromen- and chroman-type compounds (17CC13093) were disclosed. Developments in the synthesis of pentafluorosulfanyl(chromene and coumarin) derivatives (17TL4803), photoswitchable D9-tetrahydrocannabinol derivatives (17JA18206), and aminobenzopyranoxanthenes with nitrogen-containing rings (17JOC13626) have been studied.info:eu-repo/semantics/publishedVersio

Benzo[h][1,6]naftiridin türevlerinin ve kromenopirazinon iskeletinin sentezi için yeni yöntemlerin geliştirilmesi.

In the first part of this thesis, a new methodology was developed for the synthesis of benzo[h][1,6]naphthyridine derivatives. Firstly, 2-(diprop-2-ynylamino)benzaldehyde was synthesized starting from 2-aminobenzoic acid in three steps. Then, cyclization reaction was achieved in the presence of propargyl amine and DBU. The expected 3-methylbenzo[h][1,6]naphthyridine was obtained. To generalize this methodology, several derivatives of 2-(diprop-2-ynylamino)benzaldehyde were synthesized by applying Sonogashira coupling reaction in good yields. Cyclization reaction of these derivatives were succeeded by using propargyl amine and DBU. Finally, aryl and methyl substituted benzo[h][1,6]naphthyridine derivatives were obtained in good yields. In the second part, a new synthetic method for the synthesis of a chromenopyrazine and a chromenopyrazinone derivative was developed. Firstly, acetonitrile group was introduced to salicylaldehyde. Then, reaction of this aldehyde with propargyl amine gave imine. DBU-supported cyclization reaction afforded the product, 3-methyl-5H-chromeno[3,4-b]pyrazine. Finally, cyclization product was oxidized with CrO3/pyridine to yield 3-methyl-5H-chromeno[3,4-b]pyrazin-5-one. In order to generalize this reaction, two different aldehyde substituted at the benzene ring were employed. Same procedure for cyclization reaction was applied to get chromenopyrazine derivatives. Unfortunately, expected chromenopyrazine and chromenopyrazinone derivatives were not obtained.M.S. - Master of Scienc

Regioselective Synthesis of Benzo[h][1,6]- naphthyridines and Chromenopyrazinones through Alkyne Cyclization

WOS: 000397849300015A regioselective approach to the synthesis of benzo[h][1,6]-naphthyridine and chromenopyrazinone derivatives was developed. The synthetic route to benzo[h][1,6]naphthyridines involves the N-propargylation of aromatic aminobenzaldehydes, followed by reaction with propargylamine in the presence of DBU (1,8-diazabicyclo[5.4.0] undec-7ene). For the synthesis of chromenopyrazine and chromeno-pyrazinone derivatives, the acetonitrile group was introduced to salicylaldehyde derivatives, and a DBU-promoted cyclization reaction between aldehydes and propargylamine gave the chromenopyrazines. The intramolecular heterocycloaddition reaction between the triple bond and the azadiene, which is formed as an intermediate, gave the desired structures.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TBAG-112 T360]; Turkish Academy of Sciences (TUBA)Turkish Academy of Sciences; Middle East Technical University (METU)Financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) (grant no. TBAG-112 T360), the Turkish Academy of Sciences (TUBA), and the Middle East Technical University (METU) is gratefully acknowledged

Yeni Heterosiklik Sistemlerin Altın Tuzları ve İyotKatalizörlüğünde Aminoalkinlerden Çıkarak Heterosiklizasyon Yöntemi ile Tasarımı

TÜBİTAK TBAG Proje01.05.2015Heterosiklik bileşikler, iskelet yapısında bir veya birden fazla karbon atomunun farklı bir atom ile yer değiştirmiş olduğu organik bileşiklerdir. Özellikle azot atomu içeren heterosiklik bileşikler, doğal ürünlerin ve ilaçların yapısında yaygın bir şekilde bulunduklarından çok önemlidirler. Karbon ile bir heteroatom arasında oluşan bir bağ sonucunda halkalı bir yapıyı oluşturan tepkimeler genel olarak heterosiklik bileşiklerin sentezine uygulanan en önemli yöntemdir. Özellikle azot içeren bir fonksiyonel grubun bir alken veya alkine intramoleküler katılması önemli sentetik stratejilerden biridir. Eğer reaktif fonksiyonel gruplar bir organometalik reaksiyon sonucu oluşturulmuşsa yeni heterosiklik iskeletler kolay bir şekilde sentezlenebilir. Bu tip tepkimelerde önde gelen altın katalizörleri önemli derecede rol oynarlar. Bu projenin amacı alkin siklizasyonunu temel reaksiyon alarak yeni heterosiklik bileşiklerin sentezi için yeni yöntemlerin geliştirilmesidir. Bu çalışma kapsamında heteroaromatik bileşiklerden pirol ve indolden çıkarak bu bileşiklere başka heterosiklik bileşikler kenetlendi. Bunun için önce pirol ve indol azot atomlarına propargil grubu bağlandı. Azot atomuna komşu C-2 karbon atomuna ise aldehit, ester, oksim, hidrazon, ketoalkin gibi fonksiyonel gruplar takıldı. Halkalaşma tepkimesi bu fonksiyonel gruplarla propargil grubu arasında baz eşliğinde veya altın aktalizörlüğünde gerçekeştirildi. Böylece pirol ve indol halkalarına pirazol, pirazin, triazepin gibi heterosiklik bileşikler kenetlendi. Projenin bir diğer bölümünde pirol halkasının C-2 karbon atomuna pirol, pirazol ve indol gibi ikinci bir heterosiklik bileşik, azot atomuna ise propargil grubu bağlandı. Altın katalizörlüğünde veya baz eşliğinde yapılan siklizasyon tepkimeleri sonucunda üç farklı heterosiklik bileşiğin kenetlendiği yeni heterosiklik bileşikler sentezlendi. Bu yöntemler azot-atomu içeren yeni polisiklik heteroaromatik bileşiklerin sentezi için yeni bir kapı açmaktadır

Synthesis of dipyrrolo-diazepine derivatives via intramolecular alkyne cyclization

A regioselective approach was developed for the synthesis of dipyrrolo-diazepine derivatives. The synthetic route to dipyrrolo-diazepines first involves the synthesis of dipyrromethanes, followed by reaction of propargyl bromide in the presence of NaH to attach one alkyne functionality to the pyrrole nitrogen atom. Intramolecular heterocyclization with NaH in DMF between the alkyne functionality and pyrrole nitrogen atom gave the desired structures in good yields

Mechanistic Insights into the Reaction of N-Propargylated Pyrrole- and Indole-Carbaldehyde with Ammonia, Alkyl Amines, and Branched Amines: A Synthetic and Theoretical Investigation

Menges, Nurettin/0000-0002-5990-6275WOS: 000483709700031The reaction of pyrrole- and indole-carbaldehydes having a propargyl group attached to the nitrogen atom with various amines was studied. The reaction with ammonia formed pyrrolo[1,2-a]pyrazine and pyrazino[1,2-a]indole while the reaction with alkylamines such as methyl, ethyl, hexyl, and benzylamines formed the corresponding pyrazinone derivatives. Unexpectedly, the reaction with allylamine and propargylamine formed pyrazine derivatives in which the allyl and propargyl groups were removed from the molecule. On the other hand, the reaction of N-propargylated pyrrole-carbaldehyde formed indolizine derivatives upon reaction with sterically bulky adamantyl- and tert-butylamines. To understand the main factors causing these differences in reactivity, the reaction mechanisms were studied by means of computational methods. Our calculations showed that bulky amines tend to attack the central carbon of allene formed by the isomerization of N-propargyl functionality, while the attack on the carbonyl carbon by aliphatic amines is more profound