Novel applications of the hypervalent iodine chemistry. Synthesis of thiazolo-fused quinolinones

Abstract

A synthesis of thiazolo [5,4-c]quinolinone derivatives featuring the use of two different hypervalent iodine reagents has been achieved starting from ethyl benzoylacetate in an efficient way. Hydroxy(tosyloxy)phenyliodine (HITB, Koser´s reagent) has been employed to functionalize the starting β-ketoester 4, and phenyliodine(III)bis(trifluoroacetate) (PIFA) to perform a ring closure reaction on the corresponding N-methoxyamides 9 and 14.

Chemistry of Polyvalent Iodine

“…Tellitu and Domı ´nguez have developed a series of BTI-promoted intramolecular amidation reactions, generalized in Scheme 48, leading to various five-, six-, and seven-membered heterocycles 143. [340][341][342][343][344][345][346][347][348][349][350][351][352][353] Experimental evidence supports the ionic mechanism of this reaction, involving N-acylnitrenium intermediates 142 generated in the initial reaction of the amide 141 with the hypervalent iodine reagent. 340 This methodology with some variations (Scheme 48) has been utilized by Tellitu, Domı ´nguez, and co-workers in the synthesis of the following heterocyclic systems: heterocyclefused quinolinone derivatives, 341 1,4-benzodiazepin-2ones, 342 benzo-, naphtho-, and heterocycle-fused pyrrolo[2,1-c]- [1,4]diazepines, 343 2,3-diarylbenzo[b]furans, 344 quinolinone or pyrrolidinone derivatives, 345 dibenzo[a,c]phenanthridines, 346 thiazolo-fused quinolinones, 347 isoindolinone and isoquinolin-2-one derivatives, 348 indoline derivatives, 349 5-aroyl-pyrrolidinones, 350,351 and indazolone derivatives.…”

“…The cyclizations, induced by hypervalent iodine reagents, are particularly useful in the synthesis of heterocycles. Tellitu and Domínguez have developed a series of BTI-promoted intramolecular amidation reactions, generalized in Scheme , leading to various five-, six-, and seven-membered heterocycles 143 . − Experimental evidence supports the ionic mechanism of this reaction, involving N -acylnitrenium intermediates 142 generated in the initial reaction of the amide 141 with the hypervalent iodine reagent …”

“…This methodology with some variations (Scheme ) has been utilized by Tellitu, Domínguez, and co-workers in the synthesis of the following heterocyclic systems: heterocycle-fused quinolinone derivatives, 1,4-benzodiazepin-2-ones, benzo-, naphtho-, and heterocycle-fused pyrrolo[2,1- c ][1,4]diazepines, 2,3-diarylbenzo[ b ]furans, quinolinone or pyrrolidinone derivatives, dibenzo[ a,c ]phenanthridines, thiazolo-fused quinolinones, isoindolinone and isoquinolin-2-one derivatives, indoline derivatives, 5-aroyl-pyrrolidinones, , and indazolone derivatives. , Recent representative examples include the preparation of indoline derivatives 145 from anilides 144 , pyrrolidinones 147 from alkynylamides 146 , , and indazol-3-ones 149 from anthranilamides 148 (Scheme ). , …”

Advances in Synthetic Applications of Hypervalent Iodine Compounds

“…411,412 The key active species in these reactions, N-acylnitrenium intermediates 171, are initially generated from amides 170 and BTI, and the experimental evidence supports the ionic mechanism of these cyclization reactions. 413 This methodology can be used to prepare various heterocyclic compounds, such as heterocycle-fused quinolinones, 414 1,4-benzodiazepin-2-one derivatives and fused indeno-1,4-diazepinones, 415,416 benzo-, naphtho-, and heterocycle-fused pyrrolo[2,1-c][1,4]diazepines, 417 quinolinones or pyrrolidinones, 418 dibenzo[a,c]phenanthridines, 419 thiazolofused quinolinone derivatives, 420 lin-2-ones, 421 indolines, 422 5-aroyl-pyrrolidinone derivatives, 423,424 indazolones, 425 substituted indolizidinones, 426,427 1-arylpyrrolopyrazinones, 428 benzisothiazolene, 429,430 isothiazolones, 431 α-hydroxyalkyl lactam derivatives, 432 structurally diverse pyrrolo(benzo)diazepines, 433 and furopyrimidinones. 434 Representative examples include the preparation of pyrrolidinones 174 from alkynylamides 173, 423,424 benzisothiazol-3ones 176 from 2-mercaptoamides 175, 429 and hydroxyl lactams 178 from o-alkyl hydroxamates 177 (Scheme 53).…”

Synthesis of Thiazoloquinolines with Diverse Molecular Skeletons: A Review

“…The resultant thiazoles were converted to N ‐methoxyamides in three steps and finally cyclised using PIFA to form 2‐substituted‐5‐methoxythiazolo[5,4‐ c ]quinolin‐4‐ones in 90–97 % yields (Scheme 17). [56] …”