Original Article:
N-Boc-Amides in Cross-Coupling Reactions
Yann Bourne-Branchu, et al.
Chemistry-A European Journal 25.11 (2019): 2663-2674.
10.1002/chem.201802635
What Are Boc Group and Boc Protection?
A Boc group refers to a tert-butyloxycarbonyl group, which is a chemical functional group commonly used in organic synthesis. It is represented by the abbreviation Boc and consists of a tert-butyl group (a branched alkyl group with four carbon atoms) bonded to a carbonyl group (a carbon atom double-bonded to an oxygen atom). The Boc group is often used as a protecting group for amine or alcohol functional groups during chemical reactions, preventing unwanted reactions or side reactions. It can be easily removed under specific conditions, allowing the original functional group to be recovered.
N-Boc-Amides in Cross-Coupling Reactions
In the past few years, numerous studies have shown that N-Boc-amides exhibit good activity for various cross-coupling reactions. In this work, the researchers summarize a series of studies involving chemical transformations of N-Boc-amides. Here are just a few examples:
- C-O bond forming reactions
A cobalt-catalyzed system involving cobalt salts, bipyridyl ligands, and metal manganese as reducing agents was developed, which can achieve the conversion of amides to esters. Under this catalytic system, aryl, heteroaryl, or alkyl N-Boc-amides can be efficiently converted to their corresponding esters. Several primary alcohols with ether, amino, and even chloride functionality can be efficiently coupled.
Cobalt-catalyzed esterification of N-Boc aliphatic amides
- C-N bond forming reactions
Garg and co-workers reported a nickel-catalyzed transamidation coupling reaction system. In this catalytic system, various N-Boc-benzamides bearing amino, fluorine, and even heteroaryl moieties were used, and the corresponding morpholine amides were obtained in excellent yields. Furthermore, this catalytic system can also be applied to the transamidation of several aliphatic N-Boc-N-benzyl amides bearing cyclic or acyclic alkyl moieties, hindered rings and even heterocyclic moieties.
Nickel-catalyzed transamidation of N-Boc aliphatic amides
- C-B bond forming reactions
Studies have shown that the decarbonylation process can also be used to form C-B bonds. A nickel/NHC catalytic system can intercalate into the amide C-N bond to form acyl nickel (II) complexes. After the decarbonylation process, aryl nickel (II) species are formed, which can undergo transmetallation with base-activated diboron compounds. After reductive elimination, the aryl boronate is obtained. This method is very versatile as it allows the conversion of aryl, heteroaryl, alkenyl and even aliphatic N-Boc-amides into the corresponding boronate esters.
Nickel-Catalyzed Decarbonylborylation of N-Boc-amides
- Chemical transformation reactions of other N-Boc-amides
Other N-Boc-amide chemical conversion reactions include C-C(sp2) bond forming reactions, C-C(sp3) bond forming reactions, and Amide to olefin conversion. These studies demonstrate the high synthetic utility of N-Boc-amides.
Chemicals Related in the Paper:
| Catalog Number | Product Name | Structure | CAS Number | Price |
|---|---|---|---|---|
| ACM106412366 | N-Boc-cyclohexamide |  |
106412-36-6 | Price |
| ACM158861382 | N-Boc-s-tritylcystein-N-methoxy-N-methylamide |  |
158861-38-2 | Price |
| ACM166520123 | N-Boc-pierazine-2-(S)-carboxamide |  |
166520-12-3 | Price |
| ACM30044678 | N-BOC-L-ASPARAGINOL |  |
30044-67-8 | Price |
