Diastereoselective Aza‐Mislow–Evans Rearrangement of N‐Acyl tert‐Butanesulfinamides into α‐Sulfenyloxy Carboxamides

Abstract

Ad iastereoselective [2,3] rearrangement of O-silyl N-sulfinyl N,O-ketene acetals derived from chiral N-acyl tertbutanesulfinamides was developed, giving a-sulfenyloxy carboxamides with excellent enantioselectivity.E nolization and subsequent silylation of N-acyl tert-butanesulfinamides initiate this aza variant of the Mislow-Evans rearrangement, in which the chirality at the sulfur atom in the rearrangement precursors is faithfully transferred to the a-carbon stereocenter of the products.T he Ellman sulfinamide,o ften used as ac hiral ammonia equivalent, can serve in this rearrangement as ac hiral precursor for the asymmetric synthesis of a-oxygenfunctionalizedc arboxamides. Scheme 1. [2,3] Rearrangement of N-acyl tert-butanesulfinamides via O-silyl N-sulfinyl N,O-ketene acetal intermediates and related processes. Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme 3. Cleavage of the SÀOb ond of a-sulfenyloxy amides and oxidation of the tert-butanesulfenate ester. m-CPBA = m-chloroperbenzoic acid.Scheme 4. Rationalization of the observed stereochemical outcome. Angewandte Chemie Communications 15585

Trapping the Transition State in a [2,3]-Sigmatropic Rearrangement by Applying Pressure

“…The rearrangement of allylic sulfoxides to allylic sulfenate esters is a popular example of [2,3]-sigmatropic rearrangements. − This type of reaction is also known as the Mislow–Evans rearrangement − and is widely used in asymmetric synthesis due to the possibility of chirality transfer from the carbon bearing the sulfoxide group to the alcohol resulting from a subsequent reaction with an appropriate thiophile (Figure A). Hence, the Mislow–Evans rearrangement is a popular tool in the synthesis of bioactive substances and natural products like terpenes, vernolepin, , amphidinol 3, and pyrenolide D …”

Trapping the Transition State in a [2,3]-Sigmatropic Rearrangement by Applying Pressure

“…HCFF) approach to the educt of a [2,3]-sigmatropic rearrangement in both static and dynamic calculations and find that the five-membered cyclic transition state of this reaction becomes a minimum at pressures in the range between 100 and 150 GPa. Slow decompression leads to a 70:30 mix of the product and the educt of the sigmatropic rearrangement.…”

“…The rearrangement of allylic sulfoxides to allylic sulfenate esters is a popular example of [2,3]sigmatropic rearrangements. [1][2][3] This type of reaction is also known as Mislow-Evans rearrangement [4][5][6][7][8][9][10][11] and is widely used in asymmetric synthesis due to the possibility of chirality transfer from the carbon bearing the sulfoxide group to the alcohol resulting from a subsequent reaction with an appropriate thiophile (Figure 1A).…”

“…The rearrangement of allylic sulfoxides to allylic sulfenate esters is a popular example of [2,3]sigmatropic rearrangements. [1][2][3] This type of reaction is also known as Mislow-Evans rearrangement [4][5][6][7][8][9][10][11] and is widely used in asymmetric synthesis due to the possibility of chirality transfer from the carbon bearing the sulfoxide group to the alcohol resulting from a subsequent reaction with an appropriate thiophile (Figure 1A). Hence, the Mislow-Evans rearrangement is a popular tool in the synthesis of bioactive substances and natural products like terpenes, [12] vernolepin, [13,14] amphidinol 3, [15] and pyrenolide D. [16] The transition state of the Mislow-Evans rearrangement has attracted considerable attention, because it determines the stereochemistry of the reaction.…”