Synthesis of Selenium and Tellurium Ylides and Carbanions. Application to Organic Synthesis

Abstract

The preparation and synthetic applications of selenium‐ and tellurium‐stabilized carbanions as well as selenonium and telluronium ylides are reviewed. Selenium‐ and tellurium‐stabilized carbanions are prepared by deprotonation or by element/lithium exchange of the parent selenides and tellurides. Additionally, selenium‐stabilized carbanions are prepared by conjugate addition of organometallics to vinyl‐ and alkynyl selenides. Selenonium and telluronium ylides are prepared mainly by deprotonation of the parent selenonium and telluronium salts. The above‐mentioned anionic species react with electrophiles, giving intermediates, which by subsequent transformations, lead to synthetically useful products. In the case of the selenium‐stabilized carbanions, these sequences of reactions were applied in the synthesis of natural products. The tellurium counterparts were not yet explored for this purpose. Selenonium and telluronium ylides were not yet employed in total synthesis.

Selenonium Ylides: Syntheses, Structural Aspects, and Synthetic Applications

“…For the next few years in a row, a brief discussion devoted to selenonium ylides was included into the chapters from Specialist Periodical Reports, Organic Compounds of Sulfur, Selenium, and Tellurium [10][11][12][13][14][15]. A few years later, similar discussion was included into Chapter 17 of The Chemistry of Organic Selenium and Tellurium Compounds from Patai's Chemistry of Functional Groups [16]. An update of this information can be found in an analogous chapter entitled "Synthesis of selenium and tellurium ylides and carbanions: application to organic synthesis" again included in "The Chemistry of Organic Selenium and Tellurium Compounds" from Patai's "Chemistry of Functional Groups" series published in 2014 [17].…”

Ammonium Ylide Mediated Cyclization Reactions

“…The nature of the onium group as well as the degree of stabilization by the R′ group (Scheme 1) have a profound influence on the reactivity and scope of applications for the onium ylides. [3, 5–7]…”

“…[6] Besides these, As-, Se-, and Te-ylides have been used to some, but a lesser, extent. [7] One family of compounds that has attracted considerable attention for (asymmetric) transformations over the course of the last two decades are N-ylides. [8–12] As a result, one can distinguish between N(sp 2 )-based ylides such as azomethine,[9] pyridinium,[10] and triazolium ylides[11] and N(sp 3 )-based quaternary ammonium ylides.…”

Selenolatos metálicos em reações multicomponentes do tipo Michael-aldol: adutos de Morita-Baylis-Hillman e derivados

“…Tal possibilidade foi cogitada tendo como base as reações de hidrocalcogenação de ligações π. 138,139,140,141,142 Conforme demonstrado em reações de hidrocalcogenação, os calcogenóis podem ser gerados in situ realizando-se a inserção do calcogênio elementar em um reagente organometálico, seguido de tratamento da solução resultante do calcogenolato metálico com uma fonte de prótons, como água ou etanol. Apesar de desfavorável quando comparados os pkas destas espécies (tióis, selenóis e teluróis são menos ácidos que álcoois), a transferência de prótons acontece de forma bastante eficiente e, no caso da hidroteluração, aparentemente por um mecanismo radicalar.…”

“…Após este período a reação foi interrompida pela adição de solução saturada de NaCl (15 mL 172,47, 150,58, 150,48, 140,17, 13/1,/22, 136,11, 128,70, 128,36, 126,51, 126,46, 78,16, 69,14, 69,07, 18,81, 14,21 70, 136,84, 135,53, 129,51, 129,34, 129,12, 128,98, 127,39, 126,80, 118,77, 118,71, 74,00, 43,49, 41,28, 40,12, 32,59, 32,54, 25,93, 25,55, 25,41, 23,06, 22,62, 21,36, 20,65, 13,75. 77 Se RMN (57 MHz 128,63,128,34,127,01,126,48,123,14,116,24,74,43,35,78,30,79 166,47,166,22,152,89,152,48,142,90,140,02,138,46,138,21,131,72,128,35,128,23,128,07,127,47,…”