Solid-Phase Total Synthesis of Dehydrotryptophan-Bearing Cyclic Peptides Tunicyclin B, Sclerotide A, CDA3a, and CDA4a using a Protected β-Hydroxytryptophan Building Block

Abstract

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The phosphate ester group in secondary metabolites

“…The relative trans configuration of the epoxide moiety at the side chain was established from the observation of a relative small coupling constant between H2 and H3 ( J H2–H3 = 2.0 Hz), which was also in agreement with the value found in a trans -2,3-epoxyhexanoate model compound ( 3 J H,H = 1.9 Hz). 140 Recent reports by the groups of Li 141 and Taylor 142 on the total syntheses of 71 and 73 appeared and the 2′ S ,3′ R configuration at the oxirane ring was established. Surprisingly, the former authors misrepresented the absolute configuration at the glutamine residue in their report.…”

“…Two families were included in this group: ecdysone phosphates (139-141) and haplosamates (142)(143)(144)(145).…”

Recent Progress in Solid‐Phase Total Synthesis of Naturally Occurring Small Peptides

“…In addition, Taylor et al. has provided an alternative approach (Scheme 21) to prepare 138 , 146 , tunicyclin B ( 147 ), and sclerotide A ( 148 ) [83] . In this approach, β ‐( tert ‐butyldimethylsilyloxyl)‐tryptophan ( 140 ) was used as a precursor of ΔTrp in the SPPS, which could be converted to ΔTrp under acidic environment.…”

Recent applications of solid-phase strategy in total synthesis of antibiotics

“…Recently, Taylor and coworkers developed a new approach to synthesize the Z -dehydrotryptophan residue, and they completed the total synthesis of CDA3a and CDA4a with a solid phase synthesis strategy. 35 CDA3a and CDA4a share the same uncommon amino acids like dehydrotryptophan, d -hydroxyphenylglycine and d - erythro -hydroxyasparagine. The only difference between CDA3a and CDA4a is at position 10 where CDA4a has another uncommon amino acid 3-mGlu.…”