In peptide synthesis, some amino acid side chain groups are active, so side chain groups need to be protected in amino deprotection and amino acid condensation to avoid by-products. After all the condensation reactions are completed, the protective groups are removed under certain conditions.

The commonly used alkoxycarbonyl amino protecting groups are benzyloxycarbonyl (Cbz), tert butoxycarbonyl (Boc), formoxycarbonyl (Fmoc), allyloxycarbonyl (alloc), trimethylsilylethoxycarbonyl (teoc), common acyl amino protecting group :Phthaloyl (Pht)

The side chain protection of Fmoc amino acids is stable in alkaline condition and removed in acidic condition (Tfa). One of the main advantages of Fmoc protective group is that it is extremely stable to acids. In the presence of Fmoc, Boc and benzyl groups can be deprotected.

There are 20 common Fmoc amino acids :

Fmoc-Arg(Pbf)-OH 154445-77-9

The guanidine group of Arg has strong nucleophilicity and alkalinity, so it must be protected, preferably all three nitrogen groups.

Fmoc-Asn(Trt)-OH 132388-59-1

Fmoc-Gln(Trt)-OH 132327-80-1

Asparagine (ASN) and glutamine (Gln) are usually protected by Trt and removed by TFA

Fmoc-His(Trt)-OH 109425-51-6

Histidine (his) is the most easily racemized amino acid. Boc and Trt are ideal protective groups, which inhibit racemization.

Fmoc-Cys(Trt)-OH 103213-32-7

Cysteine (Cys) has a strong nucleophilic property, and the commonly used protective groups are Trt, Tbu, bzl, etc

Fmoc-Asp(OtBu)-OH 71989-14-5

Fmoc-Glu(OtBu)-OH 71989-18-9

The side chain carboxyl groups of Asp and Glu are usually protected by Tbu, and can be removed by Tfa, Tmsbr, etc.

Fmoc-Trp(Boc)-OH 143824-78-6

Fmoc-Lys(Boc)-OH 71989-26-9

Lysine (Lys) - NH3 must be protected, and Boc is commonly used

Fmoc-Ser(tBu)-OH 71989-33-8

Fmoc-Thr(tBu)-OH 71989-35-0

Fmoc-Tyr(tBu)-OH 71989-38-3

The hydroxyl groups of serine (Ser), threonine (Thr) and tyrosine (Tyr) are usually protected by tert butyl (Tbu)

Others:

Fmoc-Gly-OH 29022-11-5

Fmoc-Ala-OH 35661-39-3

Fmoc-Ile-OH 71989-23-6

Fmoc-Leu-OH 35661-60-0

Fmoc-Met-OH 71989-28-1

Fmoc-Phe-OH 35661-40-6

Fmoc-Pro-OH 71989-31-6

Fmoc-Val-OH 68858-20-8

It is very common to use Fmoc protection strategy at the amino end. In addition, Boc, Cbz, N-methyl, amino alcohol and other methods can be used to protect. In addition, there is a large supply of non natural amino acids. If there is a demand for amino acids, we can send SMS for cooperation, and samples can be provided.