Synthesis of Microcolin B, a Potent New Immunosuppressant Using an Efficient Mixed Imide Formation Reaction
摘要:
Microcolin B, a potent new immunosuppressant isolated from blue-green alga Lyngbya majuscula off the Venezuelan coast, has been made using a methyl-directed asymmetric hydrogenation reaction with rhodium on alumina catalyst on lactone 4 for the synthesis of the key (R,R)-2,4-dimethyloctanoic acid fragment 1. A new, direct mixed imide formation reaction was also developed for the production of the unusual prolylpyrrolen-2-one 2 portion of microcolin. The pentafluorophenyl ester of CBZ-proline 5 was reacted with the lithium imidate of lactam 6, providing the mixed imide in 80% yield. Coupling of acid 1 with the N-terminus of the tripeptide, followed by coupling with pyrrolylproline 2, gave microcolin B. The new mixed-imide forming reaction was also applied to a formal total synthesis of microcolin A. The pentafluorophenyl ester of TBS-protected cis-hydroxyproline was coupled with lactam 6, and the resultant imide was converted to the key pyrrolylproline made previously far microcolin A.
Total Asymmetric Synthesis of the Potent Immunosuppressive Marine Natural Product Microcolin A
摘要:
The total asymmetric synthesis of the potent immunosuppressive compound microcolin A is reported, The synthesis establishes the absolute stereochemistry of microcolin A as C-36R, C-38R, and C-4S on the basis of the diastereoselective preparation of all four possible diastereomers of the lipid region (fragment A) and diastereoselective synthesis of fragment C starting from natural L-(S)-alanine. The strategy involves a convergent assemblage of three optically pure fragments and is amenable to chemical modifications to examine structural analogs for biological study.
Highly Convergent Total Synthesis and Assignment of Absolute Configuration of Majusculamide D, a Potent and Selective Cytotoxic Metabolite from <i>Moorea sp.</i>
作者:Eduardo J. E. Caro-Diaz、Frederick A. Valeriote、William H. Gerwick
DOI:10.1021/acs.orglett.8b04050
日期:2019.2.1
The totalsynthesis of majusculamide D (MJS-D) is described, a lipopentapeptide originally isolated from Lyngbya majuscula and reisolated from a Moorea sp. MJS-D possesses selective and potent cancer cell toxicity. A scalable and convergent strategy with a minimal number of purifications produced significant quantities of MJM-D for in vivo evaluations. The absoluteconfiguration of the 1,3-dimethyl-octanamide
Synthesis of <scp>Anti‐Pancreatic</scp> Cancer Natural Product Majusculamide D and Analogues Reveals a Preliminary <scp>Structure‐Activity</scp> Relationships
The total synthesis of majusculamide D (1) was achieved from commercially available materials. In addition, we synthesized eight analogues including three stereoisomers of majusculamide D that differ in the fatty acid chain. Six analogues including a simplified analogue 29 exhibited significant nanomolar-level IC50 values against Panc-1 cells in MTT assays. A preliminary SAR analysis indicated that
majusculamide D ( 1 )的全合成是由市售材料实现的。此外,我们还合成了八种类似物,包括三种脂肪酸链不同的 majusculamide D 立体异构体。在 MTT 测定中,包括简化类似物29在内的六种类似物对 Panc-1 细胞表现出显着的纳摩尔水平 IC 50值。初步的SAR分析表明majusculamide D的C 10 和C 2− C 3 不饱和双键上的羟基对于维持对Panc-1细胞的高活性以及C 40-Me 和C 42-Me基团的定向至关重要是可以忍受的。