Preparation of enantiomerically enriched α‐aminoorganostannanes and their applications in stereoselective synthesis

Abstract

This review deals with the preparation of chiral, nonracemic α-aminoorganostannanes and their applications in asymmetric synthesis. The pioneering works in this field date back almost 20 years ago and since then extensive research has been carried out to develop efficient and selective routes to highly enantioenriched α-aminoorganostannanes. The facile Sn/Li transmetalation of these compounds by n-BuLi has led to various applications in stereoselective synthesis. Selected examples using chiral α-aminoorganostannanes as starting materials will be reported.

Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

“…The solvent was removed under vacuum. The residue was purified by column chromatography over silica gel (30 g/g of crude, hexane/EtOAc, 9:1) to afford a mixture of 1a (0.135 g, 55%) as an amber oil and 2a (16) [M + 1] + , 114 (22), 106 (100), 105 (38), 80 (32), 78 (18 2.2.3 | (4R,5R)-4-Hydroxy-4,5-dimethyl-3-((S)-1-phenylethyl)oxazolidin-2-one (12) and (4R,5S)-4-hydroxy-4,5-dimethyl-3-((S)-1phenylethyl)oxazolidinone (13) A mixture of 3a (0.880 g, 0.01 mol) and 4b (1.470 g, 0.01 mol) was placed in a threaded ACE glass pressure tube with a sealed Teflon screw cap under N 2 atmosphere. It was stirred and irradiated with MW (200 W) at 120°C for 90 minutes.…”

“…Chiral 1,3‐oxazolidin‐2‐ones have been widely used as efficient auxiliaries for the asymmetric synthesis of a large variety of enantiopure and highly functionalized carbonylic compounds . Likewise, the preparation of α‐amino alcohols and α‐amino acids has been designed based on the approach of the transformation of chiral 1,3‐oxazolidin‐2‐ones, which in turn can be obtained from optically pure α‐amino alcohols and α‐amino acids, among other substrates . The synthetic applicability of these heterocycles has increased with the development of new methods for their construction .…”

Stereoselective Synthesis of Stannylated Dehydropiperidines and Dehydroazepanes

“…The large number of compounds studied has highlighted the importance of the aglycone chain of the iminosugar both on their activity and selectivity. [1c], We decided to consider our methodology related to enantiomerically enriched α‐aminoanions for the synthesis of iminosugar C‐glycosides as a way to control both the configuration and nature of the aglycone chain. We report herein the preparation of dehydropiperidines and dehydroazepanes that are stannylated at the α‐position relative to the oxazolidinone nitrogen; these species constitute convenient scaffolds for the diastereoselective synthesis of iminosugar C‐glycosides.…”

“…We have reported an efficient ring‐opening reaction of 2‐tributylstannyl‐1,3‐oxazolidines derived from ( R ) or ( S )‐phenylglycinol that generates enantioenriched α‐stannylated N ‐protected β‐amino alcohols . When the nitrogen was protected as a carbamate and the oxygen protected as an O ‐silyl ether, the Sn/Li transmetalation reaction of these derivatives and subsequent electrophilic trapping was shown to proceed stereospecifically with retention of configuration , . The configuration at the stereogenic center was more easily controlled when N ‐α‐stannylalkyloxazolidin‐2‐ones were involved, since the ( R ) or ( S ) anionic species was obtained starting from the appropriate chiral auxiliary through a thermodynamic resolution, in agreement with Pearson's pioneering work …”

Stereodivergent Synthesis of Iminosugars from Stannylated Derivatives of (S)-Vinylglycinol

“…We then considered the Sn–Li transmetalation by n -BuLi at low temperature which can occur with complete retention of the configuration at the anionic center of an α-aminoorganotin precursor. , At higher temperatures, it is also possible to take advantage of the epimerization of the anionic center to obtain the desired compounds with high stereoselectivities and in particular when stannylated oxazolidinones are involved. , A different situation was recently reported using α-stannylated sulfonamides with cesium fluoride at 100 °C under carbon dioxide pressure which afford products with inversion of the configuration through a tin ate complex …”