English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

1,1-Ethylboration of ethynyl(trimethyl)tin affords quantitatively and selectively (E)-1trimethylstannyl-2-diethylboryl-but-1-ene 1a, which isomerizes fast at room temperature into the (Z)-isomer 2a, followed by slow isomerization into the (E/Z)-1-diethylboryl-2-trimethylstannylbut-1-enes 3a and 4a. These rearrangements are independent of the solvent (hexane, benzene, or benzene/THF) and take place at comparable rates at daylight or in the dark. A mechanism is proposed invoking hyperconjugation and three-membered cyclic structures, for which threecoordinate boron atoms as in 1a 2a are a prerequisite. In order to prove this point, hydridoborates were prepared. The reaction of a mixture (80:20) of 1a and 2a with sodium hydride gives the corresponding hydridoborates 5a and 6a, respectively, which in contrast to the boranes do not undergo further rearrangements. An extended NMR data set of the compounds 1a – 6a was measured (H, B, C, Sn NMR) and discussed. In addition, the synthesis of a mixture of the silicon analogues 1a(Si) and 2a(Si) was reproduced, the corresponding NMR data were obtained, the molecular structures were optimized by DFT methods [B3LYP/6311+G(d,p)], and relevant chemical shifts were calculated at the same level of theory.

1,1-Ethylboration of ethynyl(trimethyl)tin. (E)-1-Trimethylstannyl-2-diethylboryl-but-1-ene, isomerization and conversion into hydridoborates