863191-31-5

Upstream product

• 61550-02-5 (furan-2-yloxy)-trimethylsilane 
• 109299-92-5 3-((E)-but-2-enoyl)oxazolidin-2-one 

Relevant academic research and scientific papers

A short-step synthesis of trans-whisky lactone by an asymmetric Michael reaction

trans-Whisky lactone 6 was synthesized enantioselectively in only six steps from readily available 2-trimethylsilyloxyfurans and 3-crotonoyl-1,3- oxazolidin-2-one using an asymmetric Michael reaction as the key step.

Support effect on stereoselectivities of vinylogous mukaiyama-michael reactions catalyzed by immobilized chiral copper complexes

Chiral bis(oxazoline)- and azabis(oxazoline)-copper complexes, used as homogeneous catalysts or immobilized onto laponite, are able to catalyze vinylogous Mukaiyama-Michael reactions between 2-(trimethylsilyloxy)furan and several electron-deficient alkenes. A study of the support effect has been conducted and different changes on the diastereoselectivities and enantioselectivities has been observed. The behavior of the catalyst is different, depending on the structure of the substrate (Michael acceptor). When diethyl benzylidenemalonate was used, the major diastereomer was that with syn configuration, but the homogeneous and the heterogeneous catalysts lead to opposite enantiomers (-80% ee in solution and 38% ee in the heterogeneous phase). This change represents a support effect of ～1.8 kcal/mol. With N-(E)-but-2-enoyloxazolidinone, the most relevant change is in the diastereomer preference. In solution, the anti isomer is the major one (anti/syn = 98/2); however, in contrast, syn isomer is preferred with the immobilized catalyst (anti/syn = 19/81). This syn preference has not been previously reported in the literature. Finally, in the case of α,β-unsaturated ketones, the homogeneous catalysts are not able to induce enantioselectivity, whereas the immobilized ones lead to moderate values (up to 70%), similar to those values described in the literature with organocatalysts.

A new pyridine-2,6-bis(oxazoline) for efficient and flexible lanthanide-based catalysts of enantioselective reactions with 3-alkenoyl-2-oxazolidinones

A new pyridine-2,6-bis(oxazoline) (4) has been easily synthesised from the reaction of (1S,2S)-2-amino-1-phenylpropane-1,3-diol (1) and dimethyl pyridine-2,6-dicarboximidate (2), followed by TIPS (TIPS = triisopropylsilyl) protection of the 4′-CH2OH group. The catalysts derived from 4 and eight lanthanide(III) triflates have been tested over three reactions involving 3-acryloyl- and 3-crotonoyloxazolidinones (5a,b): the Diels-Alder (DA) reaction with cyclopentadiene, the 1,3-dipolar cycloaddition with diphenyl nitrone and the Mukaiyama-Michael reaction with 2-trimethylsilyloxyfuran. Several reactions exhibit very good enantioselectivity (ee > 90%), and the opposite enantiomers can be easily obtained simply by changing the cation. This specific feature of the ligand can be appreciated in the DA reaction of 5a, since the catalyst [ScIII(4)] gives the adduct (2′S)-9a with 99% ee, whereas the catalyst [YIII(4)] gives the opposite enantiomer with 95% ee. A rationale of the enantioselectivity is proposed on the basis of the NMR spectra of La-based complexes involving 4 and 5 as ligands.

A new and highly efficient catalyst for the enantioselective Mukaiyama-Michael reaction between (E)-3-crotonoyl-1,3-oxazolidin-2-one and 2-trimethylsilyloxyfuran

The Mukaiyama-Michael reaction between 2-trimethylsilyloxyfuran and (E)-3-crotonoyl-1,3-oxazolidin-2-one has been stereoselectively catalysed by several optically active complexes based on bis(oxazoline) (box) or pyridine bis(oxazoline) (pybox) chiral ligands and metal cations. The catalysts derived from the newly synthesised 2,6-bis[(4′R,5′R)-diphenyl-1,3-oxazolin-2′-yl]pyridine and the triflates of EuIII, LaIII, CeIV were highly efficient: The diastereoselectivity was entirely anti and the enantioselectivity was excellent (ranging from 98 to > 99%). A mechanistic insight into the nature of the activated substrate-catalyst complex was inferred studying the lanthanum complexes with 1H and 13C NMR spectroscopy. Based on these results and on the crystallographic structure of the complex between pybox and La(OTf)3, a stereochemical model is proposed to rationalise the crucial role of the substituent in position 5, suitably placed to blind the Si-face of the coordinated reagent.