Correction and removal of expression of concern: Total synthesis of tubulysin U and N14-desacetoxytubulysin H.

Correction and removal of expression of concern for 'Total synthesis of tubulysin U and N14-desacetoxytubulysin H' by Bohua Long et al., Org. Biomol. Chem., 2020, 18, 5349-5353, https://doi.org/10.1039/D0OB01109F.

Correction: Formal synthesis of cyclotheonellazole A.

Correction for 'Formal synthesis of cyclotheonellazole A' by Bohua Long et al., Org. Biomol. Chem., 2023, https://doi.org/10.1039/d3ob00038a.

Expression of concern: Total synthesis of tubulysin U and N14-desacetoxytubulysin H.

Expression of concern for 'Total synthesis of tubulysin U and N14-desacetoxytubulysin H' by Bohua Long et al., Org. Biomol. Chem., 2020, 18, 5349-5353, https://doi.org/10.1039/D0OB01109F.

Formal synthesis of cyclotheonellazole A.

A convergent procedure for the formal synthesis of cyclotheonellazole A in high yields and excellent stereoselectivity has been developed. This synthesis features an efficient preparation of O-pivaloyl-protected α-hydroxy-ß-amino amides and a one-pot process to introduce the challenging thiazole moiety. The overall synthesis is very efficient and paves the way for the preparation of analogues for drug development.

Total synthesis of tubulysin U and N14-desacetoxytubulysin H.

A concise and efficient procedure for the total synthesis of tubulysin U and N14-desacetoxytubulysin H has been developed with high stereoselectivity on a gram scale. This synthesis features an elegant cascade one-pot process to install the challenging thiazole moiety and the employment of stereoselective reductions and a series of high-yield mild reactions to ensure the requisite stereochemistry, reaction scale, and yield and to avoid the vexing epimerization occurring during peptide formation.

Total synthesis of wewakazole B.

Wewakazole B is a novel cyclodecapeptide with highly potent cytotoxic activity isolated from a sample of M. producens collected from the Red Sea. It contains nine common and three modified amino acid residues. The first total synthesis of Wewakazole B was successfully achieved on a gram scale, unambiguously confirming its structure. Notable features include the careful choice of amino acid-protecting groups and the construction of three different substituted oxazoles present in this natural product.

Correction and Removal of Expression of Concern: Highly stereoselective gram scale synthesis of all the four diastereoisomers of Boc-protected 4-methylproline carboxylates.

[This corrects the article DOI: 10.1039/C9RA06827A.].

Expression of concern: Highly stereoselective gram scale synthesis of all the four diastereoisomers of Boc-protected 4-methylproline carboxylates.

Expression of concern for 'Highly stereoselective gram scale synthesis of all the four diastereoisomers of Boc-protected 4-methylproline carboxylates' by Kehuan Sun et al., RSC Adv., 2019, 9, 32017-32020, https://doi.org/10.1039/C9RA06827A.

Highly stereoselective gram scale synthesis of all the four diastereoisomers of Boc-protected 4-methylproline carboxylates.

A general and practical synthetic process for all the four diastereoisomers of Boc-protected 4-methylproline carboxylates has been developed with essentially complete stereoselectivity on the gram scale, which represents the most diastereoselective preparation of 4-methylproline derivatives to date. This synthesis features an Evans asymmetric alkylation to elegantly establish the challenging stereochemistry of the 4-methyl group, providing valuable insights for the diastereoselective preparation of 4-substituted prolines.

Total synthesis of padanamides A and B.

The first total syntheses of padanamides A and B have been achieved, unambiguously confirming their structures.

Synthesis, characterization and antibacterial activities of some new ferrocene-containing penems.

The synthesis and structure-activity relationships of a series of new penems bearing ferrocenyl group attached to the C-2 position of the penem nucleus were described. The beta-lactanic derivatives obtained had been characterized as sodium salts, through (1)H NMR and IR, as well as through element analysis. Their in vitro antibacterial activities against both Gram-positive including meticillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria were tested. Most of the penems exhibited superior or equivalent efficacy of antibacterial activity as well as high stability to renal dehydropeptidase-I (DHP-I) compared with faropenem. In particular, the compound 14h having a heterocyclic group showed the most potent antibacterial activity.

Synthesis, characterization and in vitro antiproliferative activities of new 13-cis-retinoyl ferrocene derivatives.

In order to improve biological behavior of the retinoyl derivatives, monoarylferrocenyl alcohols 9a and 9b were synthesized by an improved Suzuki cross-coupling method and their 13-cis-retinoic acid analogues were prepared in moderate to good yields via the Mitsunobu reaction. Their structures were confirmed by IR, (1)H NMR, (13)CNMR, MS spectra and element analysis and their antiproliferative activities were determined in vitro using human cancer cell lines. The results of bioassay showed that these organometallic analogues exhibited higher antiproliferative activities than parent 13-cis-retinoic acid and other retinoyl derivatives.