Rapid Asymmetric Transfer Hydroformylation (ATHF) of Disubstituted Alkenes Using Paraformaldehyde as a Syngas Surrogate.

José A Fuentes,Matthew L Clarke,Rachael Pittaway

doi:10.1002/chem.201502049

José A Fuentes, Matthew L Clarke + Show 1 more

Open Access

https://doi.org/10.1002/chem.201502049

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Journal: Chemistry	Publication Date: Jun 25, 2015
Citations: 37	License type: cc-by

Affiliation: University of St Andrews

Abstract

As an alternative to conventional asymmetric hydroformylation (AHF), asymmetric transfer hydroformylation (ATHF) by using formaldehyde as a surrogate for syngas is reported. A catalyst derived from commercially available [Rh(acac)(CO)2] (acac=acetylacetonate) and 1,2-bis[(2S,5S)-2,5-diphenylphospholano]ethane(1,5-cyclooctadiene) (Ph-BPE) stands out in terms of both activity and enantioselectivity. Remarkably, not only are high selectivities achievable, the reactions are very simple to perform, and higher enantioselectivity (up to 96 % ee) and/or turnover frequencies than those achievable by using the same catalyst (or other leading catalysts) can be obtained by using typical conditions for AHF.

Highlights

The development of catalytic reactions that make use of surrogates for carbon monoxide is currently experiencing intense research activity.[1]
Metric reagents and the surrogate is cheap; relatively few papers demonstrate these features.[1b,c] On this basis, the transfer hydroformylation of alkenes using formaldehyde is a potentially ideal transformation,[3] but had not been reported in an enantioselective fashion.[3c] we show that asymmetric transfer hydroformylation (ATHF) can, be carried out on low-reactivity alkenes, giving products in minutes, often with high enantioselectivity
At the onset of this work, we had found that some typical easy substrates for hydroformylation, such as mono-substituted vinyl arenes, did not seem suited to ATHF, because we obtained the linear isomer as the major product

Summary

Introduction

The development of catalytic reactions that make use of surrogates for carbon monoxide is currently experiencing intense research activity.[1]. Ligands that give very reactive conventional enantioselective hydroformylation catalysts, such as Kelliphite[5a] and BOBPHOS,[5b] gave very low yields, (R,R)-Ph-BPE/[Rh(acac)(CO)2],[5c] stands out for ATHF. In the case of the cis-stilbene hydroformylation, we found that [RhCl(COD)]2 and Ph-BPE, as was used in Reference [3 c], was not an effective catalyst (2 % conversion), a significant amount of gas pressure built up (Table 1, entry 10).

Results

Conclusion