Synthesis of Aromatic Triynes as Precursors to Helicene Derivatives

2000 ◽  
Vol 65 (4) ◽  
pp. 577-609 ◽  
Author(s):  
Irena G. Stará ◽  
Adrian Kollárovič ◽  
Filip Teplý ◽  
Ivo Starý ◽  
David Šaman ◽  
...  
Keyword(s):  
General Formula ◽  
Synthetic Approach ◽  
Reaction Sequence

A general and versatile synthetic approach to a broad series of aromatic triynes as precursors to helicene derivatives has been developed. Employing a set of simple tools, triynes comprising the (phenylethynyl)benzene, 1-(phenylethynyl)naphthalene, and 1-(1-naphthylethynyl)- naphthalene moiety have been prepared in good to excellent yields throughout the whole reaction sequence. The methodology allows constructing various types of a junction between the central diarylacetylene moiety and the attached acetylene units to get the target triynes of general formula R-C≡C-CH2-X-CH2-Ar-C≡C-Ar'-CH2-X-CH2-C≡C-R or R-C≡C-CH2CH2-Ar-C≡C-Ar'-CH2CH2-C≡C-R (R = H, CH3, TMS, or TIPS; X = O, NTs, or C(CO2CH3)2; Ar/Ar' = 2-phenylene or 2-naphthylene).

scholarly journals A selective and mild glycosylation method of natural phenolic alcohols

2016 ◽  
Vol 12 ◽  
pp. 524-530 ◽  
Author(s):  
Mária Mastihubová ◽  
Monika Poláková
Keyword(s):  
Synthetic Approach ◽  
Reaction Sequence ◽  
Simple Reaction ◽  
Glycoside Synthesis ◽  
Highly Efficient ◽  
Phenolic Alcohols

Several bioactive natural p-hydroxyphenylalkyl β-D-glucopyranosides, such as vanillyl β-D-glucopyranoside, salidroside and isoconiferin, and their glycosyl analogues were prepared by a simple reaction sequence. The highly efficient synthetic approach was achieved by utilizing acetylated glycosyl bromides as well as aromatic moieties and mild glycosylation promoters. The aglycones, p-O-acetylated arylalkyl alcohols, were prepared by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied to the stereoselective glycoside synthesis. The final products were obtained by conventional Zemplén deacetylation.

A New Synthesis of l-Hydroxypipecolic Acid

Synlett ◽  
2020 ◽  
Vol 31 (04) ◽  
pp. 355-358 ◽  
Author(s):  
Zhihua Sun ◽  
Zedong Zhang
Keyword(s):  
Synthetic Approach ◽  
Preparative Synthesis ◽  
Reaction Sequence ◽  
New Synthesis

A new synthetic approach toward l-hydroxypipecolic acid is described. This reaction sequence involves eight steps overall, starting from commercially available and inexpensive l-glyceraldehyde acetal. The strategy makes use of readily available reagents and can be used as a preparative synthesis of l-hydroxypipecolic acid. Most of the reaction steps proceed with moderate-to-good yields and do not require any unusual or expensive reagents.

scholarly journals The First Total Synthesis of Aspergillusol A, an α-Glucosidase Inhibitor

2010 ◽  
Vol 5 (7) ◽  
pp. 1934578X1000500
Author(s):  
Nisar Ullah ◽  
Shamsuddeen A. Haladu
Keyword(s):  
Total Synthesis ◽  
Synthetic Approach ◽  
Reaction Sequence ◽  
Glucosidase Inhibitor

The first total synthesis of aspergillusol A, an α-glucosidase inhibitor, was accomplished in an overall high yielding reaction sequence. A convergent synthetic approach was adopted; the erythritol segment of the molecule was derived from L-arabinose, whereas hydroxyphenylpyruvic acid oxime was built up from 4-hydroxybenzaldehyde.

scholarly journals A model study of epothilone synthesis: An alternative synthetic approach to the C1-C7 fragment

2002 ◽  
Vol 67 (4) ◽  
pp. 221-228 ◽  
Author(s):  
Gojko Lalic ◽  
Danica Galonic ◽  
Radomir Matovic ◽  
Radomir Saicic
Keyword(s):  
Synthetic Approach ◽  
Protective Group ◽  
Reaction Sequence ◽  
Reaction Conditions ◽  
Model Study

In this model study an alternative synthetic approach to the C1?C7 fragment of epothilones was investigated. Starting from 4,4-dimethylcyclopentenone, a 7 step reaction sequence afforded the key intermediate 7 in 27% overall yield. Surprisingly, the attempted deprotection of latent functionalities in 7 failed, indicating the incompatibility of the ethoxyethyl protective group with the reaction conditions employed.

X-ray Structure Refinement and Vibrational Spectroscopy of Ca8Gd2 (PO4)6 O2

2013 ◽  
Vol 12 (10) ◽  
pp. 719-726
Author(s):  
R. Ayadi ◽  
Mohamed Boujelbene ◽  
T. Mhiri
Keyword(s):  
Solid State ◽  
General Formula ◽  
Vibrational Spectroscopy ◽  
Powder Diffraction ◽  
Infrared Spectra ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Unit Cell ◽  
Cell Group ◽  
X Ray

The present paper is interested in the study of compounds from the apatite family with the general formula Ca10 (PO4)6A2. It particularly brings to light the exploitation of the distinctive stereochemistries of two Ca positions in apatite. In fact, Gd-Bearing oxyapatiteCa8 Gd2 (PO4)6O2 has been synthesized by solid state reaction and characterized by X-ray powder diffraction. The site occupancies of substituents is0.3333 in Gd and 0.3333 for Ca in the Ca(1) position and 0. 5 for Gd in the Ca (2) position.  Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit-cell group analyses.

An Efficient Imine Photocyclization as an Alternative to the Pictet-Spengler Reaction for the Synthesis of AzaBenzannulated Perylenediimide Dyes

2020 ◽  
Author(s):  
Antoine Goujon ◽  
Lou Rocard ◽  
Thomas Cauchy ◽  
Piétrick Hudhomme
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Organic Solar Cells ◽  
Reaction Sequence ◽  
Large Scope ◽  
High Yields

AzaBenzannulated PDI (AzaBPDI) dyes were synthesized in high yields via a new reaction sequence involving an imine condensation followed by visible light-induced photocyclization. The large scope and efficiency of this alternative to the Pictet-Spengler reaction is demonstrated, and allows the easy preparation of dimeric AzaBPDI as potential non-fullerene acceptors for organic solar cells.

New Insights into the Nature of the Band Gap of CuGeO3 Nanoparticles: Synthesis, Electronic Structure, and Optical and Photocatalytic Properties

2019 ◽  
Author(s):  
Victor Y. Suzuki ◽  
Luís Henrique Cardozo Amorin ◽  
Natália H. de Paula ◽  
Anderson R. Albuquerque ◽  
Julio Ricardo Sambrano ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Material Design ◽  
Photocatalytic Properties ◽  
Critical Parameters ◽  
Synthetic Approach ◽  
Microwave Assisted ◽  
Theoretical Approaches ◽  
Nanoparticles Synthesis ◽  
First Time

<p>We report, for the first time, new insights into the nature of the band gap of <a>CuGeO<sub>3</sub> </a>(CGO) nanocrystals synthesized from a microwave-assisted hydrothermal method in the presence of citrate. To the best of our knowledge, this synthetic approach has the shortest reaction time and it works at the lowest temperatures reported in the literature for the preparation of these materials. The influence of the surfactant on the structural, electronic, optical, and photocatalytic properties of CGO nanocrystals is discussed by a combination of experimental and theoretical approaches, and that results elucidates the nature of the band gap of synthetized CGO nanocrystals. We believe that this particular strategy is one of the most critical parameters for the development of innovative applications and that result could shed some light on the emerging material design with entirely new properties.</p> <p><b> </b></p>

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

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