Palladium(ii)-catalyzed ortho-C–H olefination of phenylalanine and phenylethylamine derivatives directed by removable picolinamide group

Abstract

Palladium-catalyzed ortho-C–H olefination of phenylalanine and phenylethylamine derivatives assisted by a removable picolinamide group has been achieved.

Palladium(II)‐Catalyzed Sp3/Sp2γ‐ and δ‐C‐H Functionalization of Aryl Amines using 5‐Methylisoxazole‐3‐Carboxamide as Directing Group

“…Subsequently, the MICA‐aided remote δ ‐C(sp 2 )‐H amidation/cyclization of substrates 22 b , c under the Pd(II)‐catalyzed C−H amidation reaction conditions also gave the corresponding indoline derivatives 23 b , c in 50–62% yields (Scheme ). To further reveal the utility of the MICA‐aided C−H functionalization reaction, we attempted the remote δ ‐C(sp 2 )‐H alkenylation of the MICA‐based substrate 22 b with methylacrylate under the Pd(II)‐catalyzed C−H alkenylation reaction conditions, which gave the δ ‐C(sp 2 )‐H alkenylated derivative 24 a in 88% yield (Scheme ).…”

Decoding Directing Groups and Their Pivotal Role in C−H Activation

“…Zhao and co-workers published in 2017 a notable work in which they discussed palladium-catalyzed CÀ H alkenylation in the presence of ethyl acrylate, silver-I carbonate, and potassium bicarbonate. [201] The alkenylated product was successfully achieved in 89 % yield (Scheme 39).The authors also discussed a directing-group modification, mediated by a two-step procedure: amine protection using Boc 2 O, followed by hydrolysis with lithium hydroxide. A simple inversion of the position of the carbonyl group can generate another powerful amide-substrate with a structure like the picolinamides.…”

“…Zhao and co‐workers published in 2017 a notable work in which they discussed palladium‐catalyzed C−H alkenylation in the presence of ethyl acrylate, silver‐I carbonate, and potassium bicarbonate [201] . The alkenylated product was successfully achieved in 89 % yield (Scheme 39).…”

Metal‐Catalyzed C(sp2)−H Functionalization Processes of Phenylalanine‐ and Tyrosine‐Containing Peptides

“…In 2017 a complementary method developed by Zhao and co‐workers featuring the use of PA as DG enabled the selective appendance into simple Phe compounds of numerous olefins including activated alkenes such as acrylates, vinyl sulfones, phosphates and ketone derivatives but also unactivated aliphatic alkenes such as 1‐hexene, among others [27] . Whereas the use of natural unsubstituted or para ‐substituted Phe compounds and high excess of the corresponding alkenes resulted in the exclusive formation of the diolefinated products, the presence of ortho ‐ and meta ‐substituents within the aryl ring ushered in the preferential mono‐olefination event.…”