A One-Pot Allylation–Hydrostannation Sequence with Recycling of the Intermediate Tin Waste

Abstract

A one-pot allylation and hydrostannation of alkynals where the tin byproduct formed in the first step of the reaction is recycled and used in the second step of the sequence is presented. Specifically, a BF3·OEt2-promoted allylstannation of the aldehyde moiety in the alkynal is followed by the introduction of polymethylhydrosiloxane (PMHS) and catalytic B(C6F5)3, which convert the tin byproduct of the allylation into Bu3SnH, which then hydrostannates the alkyne in the molecule. (119)Sn and (11)B NMR data suggest an organotin fluoride species is formed during the allylation step and involved in the tin recycling step.

Nasopharyngeal Microbiome in Premature Infants and Stability during Rhinovirus Infection

“…The mothur OTU table was filtered (minimum of 2 sequences per OTU) and subsampled (rarefaction analysis, smallest sample size=1037 sequences) to eliminate sample size bias on community composition. OTU differential abundance tests 19 and DESeq2 negative binomial Wald test 20 were also applied for comparison. Trees for phylogenetic diversity were built using FastTree.…”

Methodologies Limiting or Avoiding Contamination by Organotin Residues in Organic Synthesis

“…Using a similar concept, the same group also achieved a onepot allylation-hydrostannylation sequence with the recycling of the tin waste generated through the allylation to carry out the hydrostannylation. 122 Mono-organotin reagents are very appealing reagents, because when used for an organic transformation, inorganic byproducts are generated at the reaction end. The latter are considered as nontoxic compounds, and the toxicity of their mono-organotin precursors is very low when compared to those of triorganotin analogues.…”

“…Using a similar concept, the same group also achieved a one-pot allylation-hydrostannylation sequence with the recycling of the tin waste generated through the allylation to carry out the hydrostannylation . Concomitant use of allyltributyltin in the presence of BF 3 ·Et 2 O at −35 °C and recycling of the tin fluoride species by B­(C 6 F 5 ) 3 and PMHS allows simultaneous allylstannation of an aldehyde and hydrostannylation of an alkyne bond when contained in the same molecule (Scheme ).…”

Recent advances in transition metal-free catalytic hydroelementation (E = B, Si, Ge, and Sn) of alkynes

“…[160][161][162] Based on this and Yamamoto's protocol, 159 Maleczka et al developed a one-pot allylation-hydrostannation sequence for the reduction of alkynals, in which tin halide as the initial product was reduced to an organotin hydride, and this tin hydride was subsequently consumed for the hydrostannation of the alkyne unit on the allylated intermediate in the catalytic system of 2 0 /PMHS (Scheme 54). 163 Under the optimal conditions [(i) BF 3 $OEt 2 and allylstannes (1 equiv. ), toluene, À35 C, $1.5 h and (ii) B(C 6 F 5 ) 3 (20 mol%), PMHS (2 equiv.…”