Enantioselective total synthesis of sacrolide A

N-to-S Acyl Transfer as an Enabling Strategy in Asymmetric and Chemoenzymatic Synthesis

The observation of thioester-mediated acyl transfer processes in nature has inspired the development of novel protein synthesis and functionalization methodologies. The chemoselective transfer of an acyl group from S-to-N is the basis of several powerful ligation strategies. In this work, we sought to apply the reverse process, the transfer of an acyl group from N-to-S, as a method to convert stable chiral amides into more reactive thioesters. To this end, we developed a novel cysteine-derived oxazolidinone that serves as both a chiral imide auxiliary and an acyl transfer agent. This auxiliary combines the desirable features of rigid chiral imides as templates for asymmetric transformations with the synthetic applicability of thioesters. We demonstrate that the auxiliary can be applied in a range of highly selective asymmetric transformations. Subsequent intramolecular N-to-S acyl transfer of the chiral product and in situ trapping of the resulting thioester provides access to diverse carboxylic acid derivatives under mild conditions. The oxazolidinone thioester products can also be isolated and used in Pd-mediated transformations to furnish highly valuable chiral scaffolds, such as noncanonical amino acids, cyclic ketones, tetrahydropyrones, and dihydroquinolinones. Finally, we demonstrate that the oxazolidinone thioesters can also serve as a surrogate for SNAC-thioesters, enabling their seamless use as non-native substrates in biocatalytic transformations.

Brønsted acid-catalysed desilylative heterocyclisation to form substituted furans

Heterocyclisation of tert-butyldimethylsilyl (TBS) protected γ-hydroxy-α,β-unsaturated ketones catalysed by para-toluenesulfonic acid (p-TSA) to form substituted furans is reported. The reaction proceeds under mild conditions at room temperature in methanol to give a range of furan products (21 examples, up to 98% yield). Mechanistic experiments suggest the reaction proceeds via in situ deprotection followed by catalytic dehydrative heterocyclisation.

[Consideration of Occupational Diversity via Academia through Studying Abroad in the UK]

Studying abroad may prove an attractive opportunity for young Japanese scientists, as it would allow them to broaden their perspectives regarding occupational diversity as a scientist. This is the first observation I made after studying abroad at the University of Oxford for two and a half years as a postdoctoral fellow. Many young scientists in the UK have got occupations not only in academia or in manufacturing industries, but also in various other business fields. Their occupational diversity seems to be considerably wider than that found among young Japanese scientists. The second feature I observed was related to my new lifestyle in the UK, which included the practice of research. It was notably different from my experiences in Japan, and it made me reconsider how to conduct my research in a more efficient manner. During my stay in the UK, I was able to identify the significance of spending time in a different culture by avoiding contact with Japanese culture as much as I could. In this essay, I introduce the details of my process of departing for the UK and my life in Oxford; it is my hope that this information will be useful for young Japanese scientists in contemplating their life plans.