Facile Synthesis of β-Amino Disulfides, Cystines, and Their Direct Incorporation into Peptides

Abstract

Herein, we report a simple and efficient methodology for the synthesis of β-amino disulfides by regioselective ring opening of sulfamidates with benzyltriethylammonium tetrathiomolybdate [BnNEt₃]₂MoS₄. Stability and reactivity of different protecting groups under the reaction conditions have been discussed. This methodology has also been extended to serine and threonine derived sulfamidates to furnish cystine and 3,3′-dimethyl cystine derivatives.

Key words

benzyltriethylammonium tetrathiomolybdate - β-amino disulfides - sulfamidates - cystine - peptides

References and Notes

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15

The nucleophilic ring opening of cyclic sulfamidates occur exclusively by S_N2 substitution resulting in inversion of configuration as demonstrated by other groups.^¹-³

16

In order to rule out the intervention of an elimination-addition mechanism in the formation of 15a,b and 20, the dehydro amino acid [Boc-ΔAbu-OMe] derived from Boc-Threo-OMe was treated with tetrathiomolybdate 1 and there was no reaction. This rules out the intermediacy of a dehydro amino acid in the formation of the product.