scholarly journals Contiguous Quaternary Carbons: A Selection of Total Syntheses

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3841
Author(s):  
Alina Eggert ◽  
Christoph Etling ◽  
Dennis Lübken ◽  
Marius Saxarra ◽  
Markus Kalesse

Contiguous quaternary carbons in terpene natural products remain a major challenge in total synthesis. Synthetic strategies to overcome this challenge will be a pivotal prerequisite to the medicinal application of natural products and their analogs or derivatives. In this review, we cover syntheses of natural products that exhibit a dense assembly of quaternary carbons and whose syntheses were uncompleted until recently. While discussing their syntheses, we not only cover the most recent total syntheses but also provide an update on the status quo of modern syntheses of complex natural products. Herein, we review (±)-canataxpropellane, (+)-waihoensene, (–)-illisimonin A and (±)-11-O-debenzoyltashironin as prominent examples of natural products bearing contiguous quaternary carbons.

2009 ◽  
Vol 2 (2) ◽  
pp. 243-258
Author(s):  
Mónica Domínguez Pérez

This study deals with children's literature translated from Castilian Spanish into Galician, Basque and Catalan by a different publisher from that of the source text, between 1940 and 1980, and with the criteria used to choose books for translation during that period. It compares the different literatures within Spain and examines the intersystemic and intercultural relations that the translations reflect. Following the polysystems theory, literature is here conceived as a network of agents of different kinds: authors, publishers, readers, and literary models. Such a network, called a polysystem, is part of a larger social, economic, and cultural network. These extra-literary considerations play an important role in determining the selection of works to be translated. The article suggests that translations can be said to establish transcultural relations, and that they demonstrate different levels of power within a specific interliterary community. It concludes that, while translations may aim to change the pre-existent relationships, frequently they just reflect the status quo.


2009 ◽  
Vol 74 (6) ◽  
pp. 887-900 ◽  
Author(s):  
Álvaro Enríquez-García ◽  
Steven V. Ley

The bengazoles are marine natural products with unique structure, containing two oxazole rings flanking a single carbon. They show very potent antifungal activity. The total syntheses of bengazole C and E are described following a convergent route which involves diastereoselective cycloaddition of an appropriately substituted nitrile oxide with a butane-1,2-diacetal-protected alkenediol as the key step.


2018 ◽  
Vol 47 (21) ◽  
pp. 8030-8056 ◽  
Author(s):  
Hiroshi Takikawa ◽  
Arata Nishii ◽  
Takahiro Sakai ◽  
Keisuke Suzuki

This review has outlined the strategies and tactics of using arynes in the total syntheses of polycyclic natural products.


2020 ◽  
Vol 37 (2) ◽  
pp. 246-275 ◽  
Author(s):  
Nengzhong Wang ◽  
Puli Saidhareddy ◽  
Xuefeng Jiang

This review surveys the total syntheses of sulfur-containing natural products where sulfur atoms are introduced with different sulfurization agents to construct related sulfur-containing moieties.


2019 ◽  
Vol 36 (11) ◽  
pp. 1589-1605 ◽  
Author(s):  
Chao Zheng ◽  
Shu-Li You

The recent enantioselective total syntheses of natural products enabled by catalytic asymmetric dearomatization reactions of indole derivatives are presented.


2016 ◽  
Vol 14 (4) ◽  
pp. 1450-1454 ◽  
Author(s):  
Zoe J. Anderson ◽  
David J. Fox

The first total syntheses of newly isolated polyazole natural products azolemycins A–D, along with the synthesis of the tetra-oxazole non-natural analogue, are described.


2021 ◽  
Vol 26 (2) ◽  
pp. 198-213
Author(s):  
Sławomir Winch

The article elaborates on a thesis that development of new functions of the Human Resource Business Partner (HR BP) generates conflicts in three areas of operation of an enterprise: the structure, organizational culture, and goal attainment strategy. A commentary on the concept of the HR BP is provided and the functions propounded within its framework are discussed. Based on qualitative research on three large enterprises in Poland, the following strategies for the introduction of changes in the HR BP are the subject of analysis, that is: maintaining the status quo in power relations, expansion of influence over time, and the policy of small steps. It was concluded that an important factor affecting selection of a strategy is the organizational culture described from the perspective of the concept of Trompenaars and Hampden-Turner.


2021 ◽  
Author(s):  
◽  
Saint Andrew Palauni Matautia

<p>Guided by both my own journey as a Pasifika student and the ideology of Tongan academic Dr. Hūfanga Okustino Māhina, this research seeks to identify ways in which indigenous knowledge can become an integral component within education, specifically design education in New Zealand. This research focuses on the struggles Pasifika students face within an aesthetic education that has within its history, a proud claim for the removal of cultural, religious and historic references from its aesthetic vocabulary. I will argue that the absence of indigenous culture, initiated by the early modernists to embrace the universal, is no longer an appropriate model within design education as it struggles to address cultural diversity in both its content and delivery. The solution, I suggest is not an “either or” scenario but a recognition that knowledge comes from many cultures and contexts. This thesis explores the indigenous beliefs of tā, time and vā, space. It identifies the relevance these and ideologies derived from them, offer design pedagogy. Using visual ethnography, indigenous research methods and photography, I investigate and document traditional indigenous ceremonies and undertake talanoa, oral histories, in order to discover the opportunities and relevance they offer design education.  Having compared and contrasted Eurocentric models and indigenous practices I identify and illustrate current initiatives that attempt to change the status quo. This thesis endeavours to tell the story of Pasifika students through a personal lens and identifies Moana ideologies that can be introduced to design curriculum that establish beneficial pathways forward for not only Maori and Pasifika students in design education but design education and thinking as a larger context. As a nexus to this research, I have designed and curated a selection of five photographs to illustrate the journey of indigenous knowledge, practice and language through design education. These photographs pay homage to my cultural ideologies, represent the narrative behind my motivations and illuminate the reciprocal need to nurture the space between Moana students and design education.</p>


Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1199
Author(s):  
Sijia Chen ◽  
Chongguo Jiang ◽  
Nan Zheng ◽  
Zhen Yang ◽  
Lili Shi

Metal-mediated cyclizations are important transformations in a natural product total synthesis. The Pauson-Khand reaction, particularly powerful for establishing cyclopentenone-containing structures, is distinguished as one of the most attractive annulation processes routinely employed in synthesis campaigns. This review covers Co, Rh, and Pd catalyzed Pauson-Khand reaction and summarizes its strategic applications in total syntheses of structurally complex natural products in the last five years. Additionally, the hetero-Pauson-Khand reaction in the synthesis of heterocycles will also be discussed. Focusing on the panorama of organic synthesis, this review highlights the strategically developed Pauson-Khand reaction in fulfilling total synthetic tasks and its synthetic attractiveness is aimed to be illustrated.


2007 ◽  
Vol 79 (4) ◽  
pp. 701-713 ◽  
Author(s):  
Yasuyuki Kita ◽  
Hiromichi Fujioka

An efficient enantioselective construction of quaternary carbons including spiro carbons is an area of intense interest due to the importance of these units as components of biologically active natural products. Prominent methods are presented for the synthesis of chiral, nonracemic quaternary carbon centers by (i) stereospecific rearrangement of optically active epoxides, (ii) enzyme-catalyzed resolution, and (iii) hypervalent iodine reagent-induced ipso-substitution of para-substituted phenol derivatives. These methods were applied to the total syntheses of fredericamycin A and discorhabdin A.


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