scholarly journals Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

2019 ◽  
Vol 15 ◽  
pp. 497-505 ◽  
Author(s):  
Grzegorz Mlostoń ◽  
Małgorzata Celeda ◽  
Katarzyna Urbaniak ◽  
Marcin Jasiński ◽  
Vladyslav Bakhonsky ◽  
...  
Keyword(s):  
Hydrobromic Acid ◽  
Room Temperature ◽  
Elemental Sulfur ◽  
Acid Anhydride ◽  
Monomeric Form ◽  
New Class ◽  
Raney Ni ◽  
In Situ Generation ◽  
Alkylation Reactions

Adamantyloxyamine reacts with formaldehyde to give N-(adamantyloxy)formaldimine as a room-temperature-stable compound that exists in solution in monomeric form. This product was used for reactions with α-hydroxyiminoketones leading to a new class of 2-unsubstituted imidazole 3-oxides bearing the adamantyloxy substituent at N(1). Their reactions with 2,2,4,4-tetramethylcyclobutane-1,3-dithione or with acetic acid anhydride occurred analogously to those of 1-alkylimidazole 3-oxides to give imidazol-2-thiones and imidazol-2-ones, respectively. Treatment of 1-(adamantyloxy)imidazole 3-oxides with Raney-Ni afforded the corresponding imidazole derivatives without cleavage of the N(1)–O bond. Finally, the O-alkylation reactions of the new imidazole N-oxides with 1-bromopentane or 1-bromododecane open access to diversely substituted, non-symmetric 1,3-dialkoxyimidazolium salts. Adamantyloxyamine reacts with glyoxal and formaldehyde in the presence of hydrobromic acid yielding symmetric 1,3-di(adamantyloxy)-1H-imidazolium bromide in good yield. Deprotonation of the latter with triethylamine in the presence of elemental sulfur allows the in situ generation of the corresponding imidazol-2-ylidene, which traps elemental sulfur yielding a 1,3-dihydro-2H-imidazole-2-thione as the final product.

In situ generation and protonation of the isocyanide/acetylene adduct: a powerful catalyst-free strategy for multicomponent synthesis of ketenimines, aza-dienes, and heterocycles

RSC Advances ◽  
2015 ◽  
Vol 5 (117) ◽  
pp. 97044-97065 ◽  
Author(s):  
Sadegh Rostamnia
Keyword(s):  
Multicomponent Reactions ◽  
Multicomponent Synthesis ◽  
New Class ◽  
Catalyst Free ◽  
In Situ Generation

In addition to isocyanide-based Ugi, Passerini, van Leusen, and Orru multicomponent reactions, a new class of isocyanide/acetylene-based multicomponent reactions, using zwitterionic adducts, have emerged as powerful methods to synthesize biologically interesting molecules.

scholarly journals One-Step Synthesis of 2-Alkenecarbodithioate Esters from Substituted Propargyl Ethers, and Their Conversion into Isothiazole Ring through a [4+1] Type Oxidative Ring Closure

2017 ◽  
Vol 12 (6) ◽  
pp. 1934578X1701200
Author(s):  
Kazuaki Shimada ◽  
Fumiya Ishikawa ◽  
Md. Ashraful Alam ◽  
Toshinobu Korenaga
Keyword(s):  
Elemental Sulfur ◽  
Ring Closure ◽  
One Step ◽  
Chloramine T ◽  
In Situ Generation

Treatment of substituted propargyl methyl ethers with a base and elemental sulfur in the presence of a thiolate ion afforded 2-alkenecarbodithioate esters in good yields. The reaction is assumed to proceed through a pathway involving in situ generation of propadienethione intermediates. Further conversion of 2-alkenecarbodithioate esters into 2,3-dihydroisothiazoles were efficiently performed by treating with chloramine-T through a [4+1] type oxidative ring closure via thiocarbonyl S-tosylimides.

scholarly journals REGIOSELECTIVE AND FACILE OXIDATIVE THIOCYANATION OF ANILINES AND INDOLES WITH TRANS-3,5‐DIHYDROPEROXY‐3,5‐DIMETHYL‐1,2‐DIOXOLANE

2014 ◽  
Vol 10 (8) ◽  
pp. 3088-3096 ◽  
Author(s):  
Davood Azarifar ◽  
Maryam Golbaghi ◽  
Mahtab Pirveisian ◽  
Zohreh Najminejad
Keyword(s):  
Room Temperature ◽  
Reaction Times ◽  
Sodium Thiocyanate ◽  
Oxidative Potential ◽  
Mild Conditions ◽  
In Situ Generation

Oxidative potential of trans‐3,5‐dihydroperoxy‐3,5‐dimethyl‐1,2‐dioxolane (DHPODMDO) has been explored in the facile thiocyanation of anilines and indoles through the efficient and in situ generation of SCN+ ion from sodium thiocyanate. The reactions proceed with regioselectivity under mild conditions at room temperature to afford the respective thiocyanate derivatives in excellent yields and low reaction times.

scholarly journals Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1081
Author(s):  
András Gy. Németh ◽  
Péter Ábrányi-Balogh
Keyword(s):  
Natural Products ◽  
Best Practices ◽  
Organic Synthesis ◽  
Elemental Sulfur ◽  
Biologically Active ◽  
Primary Amines ◽  
Pharmaceutical Ingredients ◽  
Recent Developments ◽  
In Situ Generation

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.

One-pot Nitration of Phenols under Mild and Heterogeneous Conditions

2001 ◽  
Vol 2001 (4) ◽  
pp. 140-142 ◽  
Author(s):  
Mohammad Ali Zolfigol ◽  
Mojtaba Bagherzadeh ◽  
Elahe Madrakian ◽  
Ezat Ghaemi ◽  
Abolfazl Taqian-Nasab
Keyword(s):  
Radical Cation ◽  
Nitrous Acid ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
One Pot ◽  
Oxidation Of Phenols ◽  
In Situ Generation ◽  
High Yields

Nitrophenols can be obtained via nitrosation–oxidation of phenols with Oxone®, NaNO2 and wet SiO2 at room temperature in moderate to high yields. In situ generation of HNO2 and the radical cation mechanism via the nitrous acid catalysed (NAC) pathway or hydrogen abstraction involving NO2 appear to be applicable to phenol nitration using these reagents.

scholarly journals Synthesis, Selected Transformations, and Biological Activity of Alkoxy Analogues of Lepidilines A and C

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4190
Author(s):  
Grzegorz Mlostoń ◽  
Małgorzata Celeda ◽  
Wiktor Poper ◽  
Mateusz Kowalczyk ◽  
Katarzyna Gach-Janczak ◽  
...  
Keyword(s):  
Biological Activity ◽  
Room Temperature ◽  
Elemental Sulfur ◽  
Imidazole Ring ◽  
Heterocyclic Carbenes ◽  
Naturally Occurring ◽  
Diphenyltetrazolium Bromide ◽  
Structural Analogues ◽  
Mcf 7

Condensation of diacetyl monooxime with formaldimines derived from alkoxyamines in glacial acetic acid at room temperature leads to corresponding 2-unsubstituted imidazole N-oxides bearing an alkoxy substituent at the N(1) atom of the imidazole ring. Subsequent O-benzylation afforded, depending on the type of alkylating agent, either symmetric or nonsymmetric alkoxyimidazolium salts considered as structural analogues of naturally occurring imidazole alkaloids, lepidilines A and C. Some of the obtained salts were tested as precursors of nucleophilic heterocyclic carbenes (NHCs), which in situ reacted with elemental sulfur to give the corresponding N-alkoxyimidazole-2-thiones. The cytotoxic activity of selected 4,5-dimethylimidazolium salts bearing either two benzyloxy or benzyloxy and 1-adamantyloxy groups at N(1) and N(3) atoms was evaluated against HL-60 and MCF-7 cell lines using the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Notably, in two cases of alkoxyimidazolium salts, no effect of the counterion exchange (Br− → PF6−) on the biological activity was observed.

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