Facile Synthesis of 3-Substituted Thiazolo[2,3-α]tetrahydroisoquinolines.

Sheng-Han Huang,Te-Fang Yang,Guo-Lun Zhang,Wan-Yu Huang

doi:10.3390/molecules26206126

Sheng-Han Huang, Te-Fang Yang + Show 2 more

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https://doi.org/10.3390/molecules26206126

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Journal: Molecules (Basel, Switzerland)	Publication Date: Oct 11, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: National Chi Nan University

Abstract

It was found that 4-hydroxy-2-butenoic ester (11) could not react with 3,4-dihydro-isoquinoline (4a). Individual addition reactions of γ-mercapto-α,β-unsaturated esters (18) and -unsaturated amide (19) with 3,4-dihydroisoquinolines (4) were carried out under appropriate conditions to provide the corresponding thiazolo[2,3-α]isoquinoline derivatives with good yields (up to 87%) and significant diastereomeric selectivity. The mechanism of the crucial reaction was discussed.

Highlights

We reported that oxazolo[2,3-α]tetrahydroisoquinolines 3, an analog of oxazolidine structure in quinocarcin and tetrazomine, could be synthesized via the reaction of 3,4-dihydroisoquinolines (4) with γ-hydroxy-α,β-unsaturated ketones 5 at room temperature (Scheme 1) [10,11]
Some reactants for the synthesis of the title compounds were prepared in terms of the procedures published in the literature
In order to efficiently obtain theare title compounds, the addition reaction condi- (4a, R=H)screened, and compound wereare selected as Table the reactant the model reaction

Summary

Introduction

We reported that oxazolo[2,3-α]tetrahydroisoquinolines 3, an analog of oxazolidine structure in quinocarcin and tetrazomine, could be synthesized via the reaction of 3,4-dihydroisoquinolines (4) with γ-hydroxy-α,β-unsaturated ketones 5 at room temperature (Scheme 1) [10,11]. It is noteworthy that 4-hydroxy-2-butenoic ester could not react with 3,4-dihydroisoquinoline (4a) to provide structure (Scheme 3), either This phenomenon might be due to the strong electron-donation effect of–OR2 on the carbonyl part of the ester moiety in 11, such that this compound was not versatile enough for the aza-Michael reaction with 4a. We found that the individual reaction of γ-mercapto-α,β-unsaturated esters and -unsaturated amide with 3,4-dihydroisoquinolines (4) could be carried out under green conditions to afford the corresponding thiazolo[2,3-α]isoquinolines and [14].

Results and Discussion

The of

Conclusions