Synthesis of Chiral Bicyclic Guanidinium Salts using Di(imidazole-1-yl)methanimine

Abstract

A detailed account of the synthesis of chiral bicyclic guanidinium salts is presented. This work represents the first systematic investigation of an approach toward the challenging target molecules via a key guanylation step employing di(imidazole-1-yl)methanimine (6) followed by a two-fold cyclization, which resulted in guanidinium salts 8 and 10. Factors governing the regioselectivity of the final cyclization step are discussed based on further data obtained in the course of the attempted syntheses of two additional bicyclic guanidinium salts.

A new analytical method to measure S‐methyl‐l‐methionine in grape juice reveals the influence of yeast on dimethyl sulfide production during fermentation

“…Unlabeled and labeled SMM was synthesized from l ‐methionine and l ‐methionine‐d 3 following the method described by Turočkin et al . (Scheme ).…”

“…Unlabeled and labeled SMM was synthesized from L-methionine and L-methionine-d 3 following the method described by Turočkin et al 35 (Scheme 1). L-Methionine was heated at 40 ∘ C, with CH 3 I in water for 24 h. Subsequent work-up procedures provided unlabeled SMM.…”

A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis

“…Previous syntheses of bicylic guanidines 2 and 6 – 9 started from enantiomerically pure α-amino acids [6,8,10,16–17] or from their reduction products, chiral α-amino alcohols [9,18]. In contrast, our approach used the racemic ester rac- 12 of β-phenylalanine, easily accessible in a Knoevenagel-type condensation of benzaldehyde 11 , ammonium acetate and malonic acid, followed by esterification (Scheme 1) [20–21].…”

“…1) [4], another important Brønsted base in preparative chemistry, may also act as a powerful nucleophilic catalyst [3]. Substituted analogs of TBD [5], such as the chiral compound 2 , have become popular in the field of molecular recognition, however, without being tested as catalysts [5–10]. A first example of enantioselective Michael addition has been reported for guanidine 3 , albeit with low selectivity [11].…”

Salts in Organic Synthesis: An Overview and Their Diversified Use

“…Various synthetic pathways of old salts, synthesis of new salts, modification of existing salts are reporting. Some recent reported since 2015 are, synthesis of unsymmetrical aryl (2, 4, 6-trimethoxyphenyl) iodonium salts with its scope and stability [38], synthesis of aryl (2, 4, 6-trimethoxyphenyl) iodonium trifluoroacetate salts [39], hydrogenbonding catalysis of sulfonium salts [40], difluoromethylthiolation of aryl and heteroaryl diazonium salts [41], using phosphine oxides for synthesis of quaternary phosphonium salts [42], synthesis of liquid nickel salts [43], using arenes and aryl iodides with oxone-sulfuric acid for synthesis of diaryliodonium salts [44], synthesis of N, N-diphenyl carbazolium salts [45], and using di (imidazole-1-yl) methanimine for the synthesis of chiral bicyclic guanidinium salts [46]. The various salts compound is synthesizing and reporting to check its biological activities for various disease conditions like the use of benzimidazolium salts substituted with 2hydroxyethyl and palladium complexes of it for antiproliferative activities against human cancer cell lines [47], checking cytotoxic and electronic properties of 1-(2-(Piperidin-1-yl)ethyl)-1H-benzo-d-imidazole derivatives [48], and in vitro evaluation of benzimidazolium salts for anticancer activity etc [49].…”