Theoretical and experimental study on the reaction route for the FVP of 2-thioxohexahydroquinazolinones

(S)-5-Benzyl- and 5-benzylidene-imidazo-4-one derivatives synthesized and studied for an understanding of their thermal reactivity

“…Synthesis of (S)-5-benzyl-3-(2-chloroethyl)imidazolidine-2,4dione (7) and (S)-6-benzyl-2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one (11) Our synthetic work was focused on the obtainment of 2-oxoimidazolidinones and 2-thioxoimidazolidinones substituted in position 3 by a chloroethyl group. It was expected that these molecules would suffer dehydrogenation or dehydrochlorination reactions allowing us to study the mechanisms and energetic requirements of both class of thermal reactions.…”

“…We have also reported that 1,3-heterocycles in which the sulfur atom is changed by an oxygen atom, react at higher temperatures than cis or trans-thioxo analogs when subjected to FVP (Scheme 2, 3). 10,11 As a result of the higher temperatures required for the dioxo compounds, competitive pathways open up. In the case of (S)-5-benzyl-imidazo-4-ones, this competitive pathway is a radical process that dramatically reduces the yield of the products formed by intramolecular reactions.…”

“…Synthesis of (S)-6-benzyl-2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one(11) First, compound 20 (118 mg, 0.6 mmol), 1,2-dichloroethane 16 (0.3 mL, 3.8 mmol) and Et 3 N (0.1 mL) were placed in the microwave vial and subjected to 15 min irradiation at 100 C. The reaction products were extracted to obtain the pure 6benzyl-2,3-dihydroimidazo[2,1-b]thiazol-5(6H)-one 11 (61%, global yield: 58%). In other vial, compound 20 (436.7 mg, 2.1 mmol), 1,2-dichloroethane 16 (0.3 mL, 3.8 mmol), K 2 CO 3 (815 mg, 8.2 mmol) and acetone (1.0 mL) were placed.…”

Flash Vacuum Pyrolysis (FVP) of cis‐N‐phenyl‐hexahydro‐2H‐benzo[d][1,3]oxazin‐2‐imine and Thiazin‐2‐imine Derivatives

“…In the course of our pyrolytic studies, we have focused on heterocycles such as triazines, [8,9] triazoles, and thiadiazoles, [10] dihydropyridines, [11] tetrazoles, [12] pyrrolo[1,2‐ c ]thiazoles, [13,14] imidazolidinones, [15,16] and their six‐membered analogous hexahydroquinazolines, [17,18] among others. All these compounds were analyzed from the point of view of their stability and reactivity, with the aim of generating information (e. g. Arrhenius parameters) and using FVP towards the synthesis of new compounds which, in many cases, have biological activities.…”

Evaluation of the Antioxidant Activity of Cis/Trans-N-Phenyl-1,4,4a,5,8,8a-Hexahydro-3,1-Benzoxazin-2-Imines

“…As part of our ongoing research on partially saturated 1,3-heterocycles [14,15,16,17,18], we have published the synthesis of cyclohexene-fused 1,3-oxazines with selective antibacterial and antiparasitic action along with low cytotoxic effects (compounds 1 , 2 , Figure 1) [19].…”