Synthesis, characterization and primary evaluation of the synthetic efficiency of supported vinyltins and allyltins

Methodologies Limiting or Avoiding Contamination by Organotin Residues in Organic Synthesis

“…Even though they have not really been investigated yet, supported stannylanions can in principle also be generated and used for the synthesis of reactive reagents, as supported by the results obtained in crotyltin series. 369 6.4.3.2.3.1. Use of Insoluble Polymer-Supported Organotin Reagents for Halodestannylation Reactions.…”

“…391 All of these supported tin reagents were analyzed using solidstate 119 Sn MAS NMR and 1 H/ 13 C/ 119 Sn hr-MAS NMR in 2D experiments ( 1 H/ 13 C HSQC, 1 H/ 119 Sn HSQC, and 1 H NOESY) allowing unambiguous assignment of their isomeric distribution. 369 Organotins supported by microporous organic polymers have also been used in a catalytic Stille cross-coupling, which involves the in situ formation of a vinyltin by hydrostannylation of an alkyne, allowing the reaction to be carried out with as little as 5 mol % of tributyltin chloride as tin hydride reagent precursor. 118,119 This concept that contributes to reduce the tin amount has been successfully used by Kilburn et al Thus, the vinyltin intermediates were obtained in situ by conversion of either a microporous polymer-supported dimethyl-or a dibutyltin chloride into the corresponding tin hydride, using polymethylhydrosiloxane and Na 2 CO 3 for the exchange, which was used in the hydrostannylation of an alkyne (Scheme 117).…”

“…In addition to the reduction of organic halides, which is the usual test experiment for an evaluation of the grafted reagent quality, , these supported tin hydrides can also be used in the hydrostannylation of alkynes − or in the Barton–McCombie deoxygenation of alcohols . In the latter case, a catalytic variant was reported using hydrogenosilanes for the inside regeneration of the tin hydride.…”

Synthesis of 5-Substituted 1H-Tetrazoles from Nitriles by Continuous Flow: Application to the Synthesis of Valsartan

“…Our technology was applied to the synthesis of valsartan, an angiotensin II receptor blocker, marketed by Novartis company. − The synthesis route we developed, depicted in Scheme , is a mix between newly developed steps and literature precedents. − The palladium-catalyzed Stille cross-coupling of 2-bromobenzonitrile 3 and polymer-supported tolyltin 4 performed in batch was adapted from a methodology developed earlier in our laboratory, − and afforded 5 in 86% yield. Polymer-supported tolyltin 4 was readily prepared by lithiation of 4-bromo-toluene with tert -butyllithium followed by trapping with the polymer-supported dibutyltin iodide (see Supporting Information for details).…”

Polymers for Green C–C Couplings

“…No recycling of the tin reagent was attempted. [114,115] They also used the polymersupported phenyl stannane 22 (Scheme 13) to synthesize biaryls by the Stille coupling with aryl halides. [116] In this case the polymer was reused, although an important decrease in the yield of the coupling product was observed upon recycling.…”