Search results for "Propargyl"
showing 10 items of 32 documents
Differential reactivity of fluorinated homopropargylic amino esters vs gold(I) salts. The role of the nitrogen protecting group
2015
The reaction of several homopropargyl amino esters 4, bearing aromatic substituents and a benzyl group as nitrogen substituents, with gold(I) salts gave rise to fluorinated quinolines 6 in a tandem hydroarylation-isomerization process. On the other hand, homopropargyl amino esters 7 containing a carbamate group underwent the carbonyl addition over the triple bond in the presence of gold(I) salts, rendering fluorinated oxazines 8. The use of chiral sulfoxides allowed us to develop the asymmetric version of this protocol. This two processes complete the differential reactivity showed by these types of susbtrates, depending on the nature of the nitrogen protecting group. (C) 2014 Elsevier B.V.…
Improved synthesis and application of conjugation-amenable polyols from d-mannose
2019
A series of polyhydroxyl sulfides and triazoles was prepared by reacting allyl and propargyl d-mannose derivatives with selected thiols and azides in thiol-ene and Huisgen click reactions. Conformational analysis by NMR spectroscopy proved that the intrinsic rigidity and linear conformation of the mannose derived polyol backbone is retained in the final click products in solution. Single crystal X-ray structure determination of one of the compounds prepared further verified that the linear conformation of the polyol segment is also retained in the solid state. In addition, an improved method for direct Barbier-type propargylation of unprotected d-mannose is reported. The new reaction protoc…
Synthesis of Optically Active N-(4-Hydroxynon-2-enyl)pyrrolidines: Key Building Blocks in the Total Synthesis of Streptomyces coelicolor Butanolide 5…
2021
AbstractStarting from 5-methylhexanal and (S)-configured N-propargylprolinol ethers, coupling delivered N-(4-hydroxynon-2-ynyl)prolinol derivatives as mixtures of C4 diastereomers. Resolution of the epimers succeeded after introduction of an (R)-mandelic ester derivative and subsequent HPLC separation. Alternatively, suitable oxidation gave the corresponding alkynyl ketone. Midland reagent controlled diastereoselective reduction afforded a defined configured propargyl alcohol with high selectivity. LiAlH4 reduction and Mosher analyses of the allyl alcohols enabled structure elucidation. The suitably protected products are used as key intermediates in enantioselective Streptomyces γ-butyrola…
Propargyl-functional aliphatic polycarbonate obtained from carbon dioxide and glycidyl propargyl ether.
2013
The synthesis of propargyl-functional poly(carbonate)s with different content of glycidyl propargyl ether (GPE) units is achieved via the copolymerization of propargyl glycidyl ether and carbon dioxide. A new type of functional poly(carbonate) synthesized directly from CO(2) and the glycidyl ether is obtained. The resulting polymers show moderate polydispersities in the range of 1.6-2.5 and molecular weights in the range of 7000-10 500 g mol(-1). The synthesized copolymers with varying number of alkyne functionalities and benzyl azide are used for the copper-catalyzed Huisgen-1,3-dipolar addition. Moreover, the presence of vicinal alkyne groups opens a general pathway to produce functional …
Combining oxyanionic polymerization and click-chemistry: a general strategy for the synthesis of polyether polyol macromonomers
2014
We describe a synthetic pathway to tailor-made amphiphilic macromonomers by a combination of anionic ring-opening polymerization and copper-catalyzed azide–alkyne cycloaddition (CuAAC). Linear polyglycerol and poly(glyceryl glycerol) were synthesized in a controlled manner by anionic ring-opening polymerization of ethoxyethyl glycidyl ether or isopropylidene glyceryl glycidyl ether, respectively, with narrow and monomodal molecular weight distributions (Mw/Mn < 1.20) and molecular weights ranging from 850 g mol−1 to 2500 g mol−1. After end-capping with propargyl bromide and removal of the protecting groups, the hydrophilic precursors were quantitatively clicked to a series of hydrophobic az…
Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins
1998
New linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7-mercaptocoumarin, which were condensed with chloro-ketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins 15, 16, 17, 18, 22, 23, 24, 27 and thiopyranocoumarins 28 and 29.
ChemInform Abstract: Synthesis of Methyl Derivatives of Linear and Angular Thienocoumarins and Thiopyranocoumarins.
2010
New linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7-mercaptocoumarin, which were condensed with chloro-ketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins 15, 16, 17, 18, 22, 23, 24, 27 and thiopyranocoumarins 28 and 29.
1,1-Diphenyl-4-(thiophen-2-yl)but-3-yn-1-ol
2018
The asymmetric unit of the title homopropargyl alcohol, C20H16OS, contains two independent molecules comprising a hydroxy group, a 3-(2-thiophenyl)- propargylic moiety and two aromatic rings linked to a central carbon atom. The two unique molecules are linked into a dimer by an O—HO hydrogen bond. In one molecule, the thiophene ring is disordered over two orientations rotated by 180 with a refined occupancy ratio of 0.575 (4):0.425 (4). The crystal structure is stabilized by O—H and C—H hydrogen-bond interactions. The crystal studied was a two-component non-merohedral twin, the refined ratio of the twin components being 0.575 (4):0.425 (4). UCR::Vicerrectoría de Docencia::Ciencias Básicas::…
Mono‐ and Bis(imidazolidinium ethynyl) Cations and Reduction of the Latter To Give an Extended Bis‐1,4‐([3]Cumulene)‐p-carboquinoid System
2017
An extended π-system containing two [3]cumulene fragments separated by a p-carboquinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis(imidazolidinium ethynyl) cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carboquinoid as a result of the π-accepting properties of the capping NHCs. peerReviewed
One-pot cross-enyne metathesis (CEYM)-Diels-Alder reaction of gem-difluoropropargylic alkynes.
2013
Propargylic difluorides 1 were used as starting substrates in a combination of cross-enyne metathesis and Diels–Alder reactions. Thus, the reaction of 1 with ethylene in the presence of 2nd generation Hoveyda–Grubbs catalyst generates a diene moiety which in situ reacts with a wide variety of dienophiles giving rise to a small family of new fluorinated carbo- and heterocyclic derivatives in moderate to good yields. This is a complementary protocol to the one previously described by our research group, which involved the use of 1,7-octadiene as an internal source of ethylene.