Polypeptides. Part XIII. The use of β-methylthioethyl esters for the protection of carboxyl groups in peptide synthesis

Amaral, M. Joaquina S. A.; Barrett, G. C.; Rydon, H. N.; Willett, J. E.

doi:10.1039/j39660000807

Cited by 12 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All starting materials were easily available in moderate to good yields from the corresponding N -phthaloyl amino acids according to literature methods described for MTM ( m = 1) , and MTE ( m = 2) ester derivatives 1 Preparation of the Starting Materials …”

Section: Resultsmentioning

confidence: 99%

“…The starting materials were synthesized from the N -phthaloyl amino acids according to literature procedures by Mora et al, Dossena at al., and Amaral and Rydon . The photochemical reactions were performed in Pyrex vessels (100−250 mL) using a RPR-208 Rayonet photochemical reactor equipped with 3000 Å lamps (approximately 800 W) at 13 °C under a nitrogen atmosphere.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹

2000

View full text Add to dashboard Cite

The photochemistry of five linear methylthiomethyl (MTM)-esters of omega-phthalimido carboxylic acids Pht=N-(CH(2))(n)()COOCH(2)SCH(3) 1a-e (n = 1, 2, 3, 5, and 10), of the two methylthioethyl (MTE)-esters Pht=N-(CH(2))(n)()COOCH(2)CH(2)SCH(3) 2a,b (n = 1, 2), and of the two methyl-substituted MTM/MTE esters 3a and 3b was investigated. Two reaction channels were observed: (i) photocyclization to give medium-sized and macrocyclic rings, (ii) photochemical deprotection to give the free carboxylic acids. Photocyclization of 1b and 1c (n = 2, 3) resulted in 4b,c in excellent yields whereas the substrates 1a and 1d,e with shorter as well as longer spacer groups (n = 1, 5, 10) gave preferentially the deprotected products 5a,d,e. Subsequent photolysis afforded N-methylphthalimide (6) from 5a. The MTE-esters 2a and 2b gave the macrocyclic lactones 7 and E-8. Thus, the competition between cyclization and deprotection strongly depended on the chain length of the hydrocarbon linker between phthalimido chromophore and ester group. To examine the influence of the position of the ester group in the linker chain the model substrates 3a and 3b with identical number of atoms separating electron donor and acceptor group were investigated. The more flexible MTE-derivative 3b cyclized to give a 4:1 diastereoisomeric mixture of cis/trans-9b, whereas photolysis of the more reluctant MTM-ester 3a resulted in cis-9a only after prolonged irradiation. These results show that MTM can function as a photolabile protecting group whereas MTE cannot be removed photochemically. The distance dependence of the secondary reaction steps indicates that the primary electron transfer is not necessarily induced starting from close contact geometries.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹

2000

View full text Add to dashboard Cite

show abstract

“…The use of some alkylthioalkyl groups to protect the carboxyl of amino acids has been considered in the past (1,2). The synthesis of the esters was performed on N-protected amino acids and required the use of special reagents such as chloroalkyl or hydroxyalkyl sulphides, in the presence of bases (3).…”

mentioning

confidence: 99%

Methylthiomethyl, a new carboxyl protecting group in peptide synthesis

Dossena

Palla

Marchelli

et al. 1984

International Journal of Peptide and Protein Research

View full text Add to dashboard Cite

show abstract

Protection for the Carboxyl Group

Wuts

Greene²

2006

Greene's Protective Groups in Organic Synthesis

View full text Add to dashboard Cite

Polypeptides. Part XIII. The use of β-methylthioethyl esters for the protection of carboxyl groups in peptide synthesis

Cited by 12 publications

References 0 publications

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹

Methylthiomethyl, a new carboxyl protecting group in peptide synthesis

Protection for the Carboxyl Group

Contact Info

Product

Resources

About

Polypeptides. Part XIII. The use of β-methylthioethyl esters for the protection of carboxyl groups in peptide synthesis

Cited by 12 publications

References 0 publications

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection1

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection1

Methylthiomethyl, a new carboxyl protecting group in peptide synthesis

Protection for the Carboxyl Group

Contact Info

Product

Resources

About

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹

Photochemistry of MTM- and MTE-Esters of ω-Phthalimido Carboxylic Acids: Macrocyclization versus Deprotection¹