54 research outputs found

    Atropselective syntheses of (-) and (+) rugulotrosin A utilizing point-to-axial chirality transfer

    Full text link
    Chiral, dimeric natural products containing complex structures and interesting biological properties have inspired chemists and biologists for decades. A seven-step total synthesis of the axially chiral, dimeric tetrahydroxanthone natural product rugulotrosin A is described. The synthesis employs a one-pot Suzuki coupling/dimerization to generate the requisite 2,2'-biaryl linkage. Highly selective point-to-axial chirality transfer was achieved using palladium catalysis with achiral phosphine ligands. Single X-ray crystal diffraction data were obtained to confirm both the atropisomeric configuration and absolute stereochemistry of rugulotrosin A. Computational studies are described to rationalize the atropselectivity observed in the key dimerization step. Comparison of the crude fungal extract with synthetic rugulotrosin A and its atropisomer verified that nature generates a single atropisomer of the natural product.P50 GM067041 - NIGMS NIH HHS; R01 GM099920 - NIGMS NIH HHS; GM-067041 - NIGMS NIH HHS; GM-099920 - NIGMS NIH HH

    Growing up to belong transnationally : parent perceptions on identity formation among Latvian emigrant children in England

    Get PDF
    As a result of the wide availability of social media, cheap flights and free intra-EU movement it has become considerably easier to maintain links with the country of origin than it was only a generation ago. Therefore, the language and identity formation among children of recent migrants might be significantly different from the experiences of children of the previous generations. The aim of this paper is to examine the perceptions of parents on the formation of national and transnational identity among the ‘1.5 generation migrant children’ – the children born in Latvia but growing up in England and the factors affecting them. In particular, this article seeks to understand whether 1.5 generation migrant children from Latvia construct strong transnational identities by maintaining equally strong ties with their country of origin and mother tongue and, at the same time, intensively creating networks, learning and using the language of the new home country. The results of 16 semi-structured in-depth interviews with the parents of these children reveal that the 1.5 generation Latvian migrants are on a path of becoming English-dominant bilinguals. So far there is little evidence of the development of a strong transnational identity among 1.5 generation migrant children from Latvia. Instead, this study observed a tendency towards an active integration and assimilation into the new host country facilitated by their parents or occurring despite their parents’ efforts to maintain ties with Latvia. These findings suggest that rather than the national identity of the country of origin being supplemented with a new additional national identity – that of the country of settlement – the identity of the country of origin becomes dominated by it instead
    corecore