Regioselective synthesis of naphthoquinone/naphthoquinol–carbohydrate hybrids by [4 + 2] anionic annulations and studies on their cytotoxicity

2016 ◽  
Vol 14 (45) ◽  
pp. 10636-10647 ◽  
Author(s):  
Soumen Chakraborty ◽  
Gaurav Das ◽  
Surajit Ghosh ◽  
Dipakranjan Mal
Keyword(s):  
Regioselective Synthesis ◽  
Novel Approach

A novel approach for the synthesis of naphthoquinone/naphthoquinol–carbohydrate hybrids using the Hauser annulation as the key synthetic step has been described.

Regioselective synthesis of functionalized dihydroisoquinolines from o-alkynylarylaldimines via the Reformatsky reaction

2016 ◽  
Vol 14 (41) ◽  
pp. 9896-9906 ◽  
Author(s):  
Tohasib Yusub Chaudhari ◽  
Urvashi Urvashi ◽  
Sandeep K. Ginotra ◽  
Pooja Yadav ◽  
Gulshan Kumar ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Regioselective Synthesis ◽  
Reformatsky Reaction ◽  
Novel Approach ◽  
The Reformatsky Reaction

A novel approach for the synthesis of functionalized 1,2-dihydroisoquinolines from o-alkynylarylaldimines via the Reformatsky reaction without the aid of an external Lewis acid has been described.

Discovery of Novel Approach for Regioselective Synthesis of Thioxotriaza-Spiro Derivatives via Oxalic Acid

Synlett ◽  
2019 ◽  
Vol 30 (17) ◽  
pp. 2004-2009 ◽  
Author(s):  
Vindya K. Gopinatha ◽  
Hassan A. Swarup ◽  
Sathees C. Raghavan ◽  
Kempegowda Mantelingu ◽  
Kanchugarakoppal S. Rangappa
Keyword(s):  
Oxalic Acid ◽  
Spiro Compounds ◽  
Regioselective Synthesis ◽  
Amino Group ◽  
Subsequent Reaction ◽  
Unsaturated Ketones ◽  
Novel Approach ◽  
Spiro Derivatives ◽  
One Step ◽  
Acid Catalyzed

A vital approach for the synthesis of a range of novel thioxotriaza-spiro derivatives is described. These new heterocyclic systems are obtained via oxalic acid catalyzed reaction of α,β-unsaturated ketones in the presence of 5,6-diamino-2-mercaptopyrimidine-4-ols; thus, spiro rings are constructed in one step. Notably, this transformation involves condensation of an amino group followed by enamine reaction with alkenes and subsequent reaction promoted by oxalic acid to afford spiro compounds with excellent regioselectivity.

A novel approach to carbohydrate clusters: the regioselective synthesis of non-glycosidically linked oligosaccharides

1997 ◽  
Vol 75 (7) ◽  
pp. 983-995 ◽  
Author(s):  
Hassan Namazi ◽  
T. Bruce Grindley
Keyword(s):  
Room Temperature ◽  
Membered Ring ◽  
Regioselective Synthesis ◽  
Tertiary Amines ◽  
Excellent Yield ◽  
Novel Approach ◽  
Reaction Stoichiometry ◽  
Cis And Trans ◽  
Acylation Reactions

Dialkylstannylene acetals derived from a number of different carbohydrates having both cis- and trans-1,2-diols free were reacted with diacyl chlorides and disulfonyl chlorides in the presence of tertiary amines at room temperature to give symmetrical non-glycosidically linked disaccharides with excellent regioselectivity and in excellent yield. The regioselectivity obtained was the same as that previously found in acylation reactions of the same substrates. In one case, a symmetric non-glycosidically linked diasaccharide was also obtained in excellent yield. For methyl 4,6-O-benzylidene-α-D-glucopyranoside, a 16-membered ring macrocyclic tetralactone was obtained in 50% yield by altering the reaction stoichiometry and performing the reaction at 80 °C. Keywords: carbohydrates, clusters, non-glycosidically linked oligosaccharides, disaccharides, trisaccharides.

Conjugate systems in the construction of heterocycles and quaternary stereocenters

2007 ◽  
Vol 79 (2) ◽  
pp. 181-191 ◽  
Author(s):  
Carlos González-Romero ◽  
Pablo Bernal ◽  
Fabiola Jiménez ◽  
María del Carmen Cruz ◽  
Aydeé Fuentes-Benites ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Intramolecular Cyclization ◽  
Regioselective Synthesis ◽  
The Novel ◽  
One Pot ◽  
Naturally Occurring ◽  
Novel Approach ◽  
Michael Acceptors ◽  
Quaternary Stereocenters ◽  
Synthetic Application

The synthetic application of 4,5-bis-alkylidene-1,3-oxazolidin-2-ones led to the efficient and regioselective synthesis of 2-(3H)-benzoxazolones and diarylamines with a short methodology. They were also valuable synthons in a total synthesis of naturally occurring carbazoles. New enantiopure 4-oxazoline-2-one and 4-methylene-2-oxazolidinone were prepared via a one-pot microwave (MW)-promoted condensation of α-ketols and an enantiopure isocyanate. These enamides were efficient nucleophiles when added to Michael acceptors to give a series of compounds with quaternary stereocenters in fairly good stereoisomeric ratios. The novel approach for the synthesis of benzofurans and indoles by intramolecular cyclization of enaminones has been applied in the preparation of furobenzofurans starting from benzo-bis-enaminones.

Copper-dependent ATP7B up-regulation drives the resistance of TMEM16A-overexpressing head-and-neck cancer models to platinum toxicity

2019 ◽  
Vol 476 (24) ◽  
pp. 3705-3719 ◽  
Author(s):  
Avani Vyas ◽  
Umamaheswar Duvvuri ◽  
Kirill Kiselyov
Keyword(s):  
Oxidative Stress ◽  
Head And Neck ◽  
Transcriptional Activation ◽  
Platinum Resistance ◽  
Mrna Levels ◽  
Strong Positive Correlation ◽  
Platinum Compounds ◽  
Copper Chelation ◽  
Novel Approach ◽  
Cancer Models

Platinum-containing drugs such as cisplatin and carboplatin are routinely used for the treatment of many solid tumors including squamous cell carcinoma of the head and neck (SCCHN). However, SCCHN resistance to platinum compounds is well documented. The resistance to platinum has been linked to the activity of divalent transporter ATP7B, which pumps platinum from the cytoplasm into lysosomes, decreasing its concentration in the cytoplasm. Several cancer models show increased expression of ATP7B; however, the reason for such an increase is not known. Here we show a strong positive correlation between mRNA levels of TMEM16A and ATP7B in human SCCHN tumors. TMEM16A overexpression and depletion in SCCHN cell lines caused parallel changes in the ATP7B mRNA levels. The ATP7B increase in TMEM16A-overexpressing cells was reversed by suppression of NADPH oxidase 2 (NOX2), by the antioxidant N-Acetyl-Cysteine (NAC) and by copper chelation using cuprizone and bathocuproine sulphonate (BCS). Pretreatment with either chelator significantly increased cisplatin's sensitivity, particularly in the context of TMEM16A overexpression. We propose that increased oxidative stress in TMEM16A-overexpressing cells liberates the chelated copper in the cytoplasm, leading to the transcriptional activation of ATP7B expression. This, in turn, decreases the efficacy of platinum compounds by promoting their vesicular sequestration. We think that such a new explanation of the mechanism of SCCHN tumors’ platinum resistance identifies novel approach to treating these tumors.

Collecting Words: A Clinical Example of a Morphology-Focused Orthographic Intervention

2020 ◽  
Vol 51 (3) ◽  
pp. 544-560 ◽  
Author(s):  
Kimberly A. Murphy ◽  
Emily A. Diehm
Keyword(s):  
Written Language ◽  
Morphological Knowledge ◽  
English Orthography ◽  
Word Level ◽  
Novel Approach ◽  
Language Pathology ◽  
The One ◽  
Critical Intervention ◽  
Reading And Spelling ◽  
Reading And Spelling Difficulties

Purpose Morphological interventions promote gains in morphological knowledge and in other oral and written language skills (e.g., phonological awareness, vocabulary, reading, and spelling), yet we have a limited understanding of critical intervention features. In this clinical focus article, we describe a relatively novel approach to teaching morphology that considers its role as the key organizing principle of English orthography. We also present a clinical example of such an intervention delivered during a summer camp at a university speech and hearing clinic. Method Graduate speech-language pathology students provided a 6-week morphology-focused orthographic intervention to children in first through fourth grade ( n = 10) who demonstrated word-level reading and spelling difficulties. The intervention focused children's attention on morphological families, teaching how morphology is interrelated with phonology and etymology in English orthography. Results Comparing pre- and posttest scores, children demonstrated improvement in reading and/or spelling abilities, with the largest gains observed in spelling affixes within polymorphemic words. Children and their caregivers reacted positively to the intervention. Therefore, data from the camp offer preliminary support for teaching morphology within the context of written words, and the intervention appears to be a feasible approach for simultaneously increasing morphological knowledge, reading, and spelling. Conclusion Children with word-level reading and spelling difficulties may benefit from a morphology-focused orthographic intervention, such as the one described here. Research on the approach is warranted, and clinicians are encouraged to explore its possible effectiveness in their practice. Supplemental Material https://doi.org/10.23641/asha.12290687

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