Asymmetric total synthesis of botcinins C, D, and F

Stereoselective total synthesis of botcinins C, D, and F is effectively carried out through asymmetric aldol reactions, 6-endo ring closure, and SmI2-mediated 3,4-trans or -cis stereoselective intramolecular Reformatsky reaction. Rapid esterification of the main skeleton of botcinins with the chiral side chain using MNBA and DMAP produced botcinin D, an antifungal chemical against a pathogen of rice blast disease.     

Stereoselective total synthesis of reveromycin B and C19-epi-reveromycin B

Our studies toward the total synthesis of the reveromycin family of natural products are described herein. Our synthetic approach is efficient, stereocontrolled, and convergent and has resulted in the first synthesis of reveromycin B (4) and C19-epi-reveromycin B (55). Key steps of this successful strategy include: a modified Negishi coupling (construction of C7-C8 bond) and a Kishi-Nozaki reaction (construction of C19-C20 bond), which were employed in the attachment of the target side chains. The key building blocks for the total synthesis were thus defined as vinyl iodide 6, alkyne 7, and alkyne 8. Our synthesis illustrates the utility of the modified Negishi coupling for the construction of complex dienes, confirms the proposed stereochemistry of reveromycins and paves the way for the preparation of designed analogues for biological study.     

Structural revision and total synthesis of caraphenol B and C

Chemical syntheses of two stereochemically unique resveratrol dimers, caraphenols B and C, have shown that their structures are misassigned. Thoughts on their potential chemical etiology led to an alternate structural proposal that has been confirmed through synthesis, one indicating that the substituents on their respective indane systems exist in a relative trans,trans orientation rather than the originally postulated all-cis arrangement.     

Total synthesis of maremycins A,B, C1/C2, D1, and D2

The total synthesis of maremycins A, B, C₁/C₂, D₁, and D₂ is achieved starting from the natural amino acids l-isoleucine and S-methyl-l-cysteine, in which the total synthesis of maremycins B, C₁/C₂, and D₂ is accomplished for the first time. The synthesis features a position-selective intramolecular bromination process for the synthesis of key chiral building block, a Pd-catalyzed indole synthesis for the preparation of (2S,3S)-β-methyltryptophan and hydroxylation of oxindoles by molecular oxygen. In addition, the protocol for conversion of maremycins A and B to maremycins C and D was improved.     

The first total synthesis and determination of the absolute configuration of chapecoderin A, B and C

The seco- and rearranged-labdanes, chapecoderins A 1, B 2, and C 3 have been synthesized for the first time starting from (S)-(+)-Wieland-Miescher ketone analogue 11. Their absolute configurations have been determined as depicted in the structures 1, 2 and 3.     

The total synthesis of tubulysin D

The first total synthesis of tubulysin D is reported. The development and application of new tert-butanesulfinamide methods allowed for rapid syntheses of the tubuvaline and tubuphenylalanine fragments. Most significantly, a route was devised and implemented to introduce and carry forward the highly labile N,O-acetal functionality. Tubulysin D is the most active member of the tubulysin family, and the efficient synthetic route described herein will allow for the rapid syntheses of analogues to probe the biological activity of this important class of natural products.     

The total synthesis of strobilurin B

A new regio- and stereocontrolled total synthesis of the antibiotic strobilurin B is performed in nine steps in 5.5% overall yield.     

The total synthesis of pantocin B

[reaction: see text] Pantocin B, an unusual antibiotic produced by Erwinia herbicola, effectively controls E. amylovora, the pathogen causing the plant disease fire blight. A total synthesis of pantocin B from L-alanine, glycine, and L-malic acid is reported.     

The first total synthesis of xenitorins B and C: assignment of absolute configuration

Starting from (-)-beta-pinene, the first total synthesis of xenitorins B and C has been accomplished, which also allowed the assignment of their absolute configuration.     

A concise total synthesis of arizonins B1 and C1

A concise and efficient total synthesis of arizonins B1 and C1 is reported. A key building block alkyne is synthesized from d-glucono-δ-lactone and used in the Dötz benzannulation reaction to construct the naphthalene unit. An oxa-Pictet–Spengler reaction gave the pyran ring while an H₂SO₄ mediated isomerization set the correct stereochemistry of the target molecules. Alternatively, a direct anti-pyran stereochemistry was prepared in a TFA solvent. The synthesis is competitive to previous reports and marks the first enantioselective synthesis of arizonin B1.     

Enantioselective total synthesis of iso-cladospolide B, cladospolide C and cladospolide B from tartaric acid

The enantioselective synthesis of the natural products cladospolide B, cladospolide C, and iso-cladospolide B has been accomplished from tartaric acid. Key reactions in the synthetic sequence include the elaboration of a γ-hydroxy amide derived from tartaric acid via alkene cross metathesis, Yamaguchi lactonization, and ring closing metathesis.     

The first total synthesis of trichostatin D

Trichostatin D and 6-epi-trichostatin D have been stereoselectively synthesized through a remote stereoinduction with a chiral vinylketene silyl N,O-acetal and glycosylation of hydroxyimide under Mitsunobu conditions.     

The stereoselective total syntheses of pectinolides A,B, and C

The stereoselective total synthesis of pectinolide B has been accomplished for the first time along with total syntheses of pectinolides A and C. MacMillan α-hydroxylation and Sharpless asymmetric dihydroxylation reactions are involved in generating the three stereogenic centers. Other important transformations in the synthesis are Z-selective Still–Gennari olefination, selective benzylation of the homoallylic alcohol, and a one-pot MOM deprotection followed by lactonization leading to all three pectinolides A–C being synthesized from a common intermediate. Pectinolides A, B, and C were synthesized from n-hexanal in 19, 20, and 18 steps with overall yields of 8.8%, 6.72%, and 9.2%, respectively.     

The total synthesis of the annonaceous acetogenin, muricatetrocin C

The total synthesis of the potential antitumour agent muricatetrocin C has provided an ideal stage for the exploitation and development of new chemistry. A convergent synthetic strategy has been realised incorporating three distinct pieces of methodology, these include a highly diastereoselective hetero-Diels-Alder reaction to construct the butenolide terminus, an oxygen to carbon rearrangement to install the trans-2,5-disubstituted tetrahydrofuran ring and a spatial desymmetrisation process to afford the anti-diol unit.     

The first total synthesis of sporiolide B

The first total synthesis of natural cytotoxic agent, sporiolide B, is described. d-Xylose was used as the chiral template to pre-control the absolute configuration during the synthesis. Yamaguchi esterification and ring closing metathesis greatly facilitate the target compound accomplishment.     

The enantioselective total synthesis of laurendecumallene B

For decades, the Laurencia family of halogenated C₁₅-acetogenins has served as a valuable testing ground for the prowess of chemical synthesis, particularly as it relates to generating functionalized 8-membered bromoethers. Herein, we show that a readily modified and predictable approach that generates such rings and an array of attendant stereocenters via a bromenium-induced cyclization/ring-expansion process can be used to synthesize laurendecumallene B and determine the configuration of two of its previously unassigned stereocenters. In particular, this work highlights how the use of the bromenium source BDSB (Et₂SBr·SbCl₅Br) in non-conventional solvents is essential in generating much of the target''s complexity in optimal yields and stereoselectivity. Moreover, the final structural assignment of laurendecumallene B reveals that it has one element of bromine-based chirality that, to the best of our knowledge, is not shared with any other member of the class.

Use of two key reactions initiated by BDSB (Et₂SBr·SbCl₅Br) affords an efficient total synthesis of laurendecumallene B, establishing the configuration of its two bromine-bearing stereocenters.