Electrophile‐Mediated Reactions of Functionalized Propargylic Substrates

Abstract

Metal-free halogen, chalcogen, or oxocarbenium ion mediated yne-carbonyl or yne-thioxo transformations of a range of N-and O-propargylic compounds have been studied. This investigation has led to the development of a mild, economic, and effective method for the synthesis of functionalized 4H-

N-Propargylamines: versatile building blocks in the construction of thiazole cores

“…On the other hand internal N -propargylamines 55 under the same reaction conditions gave a mixture of 57 and 56 ; (4) arylideneoxonium ion-mediated cyclization of internal N -propargylamines 55 afforded exclusively the corresponding 4 H -1,3-thiazines 56 in good yields. However, terminal N -propargylamines failed to participate in this reaction [ 99 ].…”

Transition Metal‐Free Synthesis of Carbo‐ and Heterocycles via Reaction of Alkynes with Organylchalcogenides

“…In an extension of their previous studies, the same research group disclosed the electrophilic cyclization of alkynes bearing amide 16 , carbamates 17 and 18 , urea 19 , thiourea 20 , and ester 21 as substituents (Figure 1). [37] The simultaneous formation of a 6‐membered or a 5‐membered ring with the installation of iodine, phenylselenium, and 3,4‐dihydroisochromene was explored. In this study, when PhSeCl was employed as an electrophile source, internal alkynes bearing electron‐rich aryl rings reacted via a 6‐ endo ‐dig mode, while electron‐poor substituents or terminal alkynes cyclized by a 5‐ endo process.…”

Formation of Hindered Arylcarbamates using Alkyl Aryl Carbonates under Highly Reactive Conditions

“…Even the most hindered O -tertiary carbamate can be readily prepared using the method. 16 Electron deficient arylamines are equally good substrates as electron rich ones although in some cases special means such as high temperature, long reaction time, catalysts and microwave irradiation were used for the former. 17 The major drawback is the difficulty to prepare the dialkyl dicarbonates, which requires multiple step synthesis and involves using toxic phosgene or triphosgene.…”

“…The other method is to use dialkyl dicarbonates. Even the most hindered O ‐tertiary carbamate can be readily prepared using the method . Electron deficient arylamines are equally good substrates as electron rich ones although in some cases special means such as high temperature, long reaction time, catalysts and microwave irradiation were used for the former .…”