Abstract:Dedicated to Professor Dieter Seebach on the occasion of his 65th birthdayThe synthesis of a range of 3-(phenylsulfonimidoyl)propanoate derivatives is described. A number of strategies for the imination of the key sulfoxide methyl 3-(penylsulfinyl)propanoate are discussed including the use of O-(mesitylsulfonyl)hydroxylamine (MSH) and iminoiodane reagents (PhÀINÀSO 2 R). A successful strategy for the preparation of the target compounds was the use of MSH followed by in situ coupling with a NBoc-protected amino… Show more
N-heterocyclic carbene catalyzed Michael additions have been revisited with 1,3-dialkyl- or 1,3-diarylimidazol(in)ium-2-carboxylates, that is, NHC·CO2 adducts, as the source of the free NHC catalysts in solution. Using these precatalysts, a number of efficient carba-, sulfa-, and phospha-Michael additions were achieved very conveniently, without the need for an external strong base to generate the NHC by deprotonation of an azolium salt. To further expand the scope of the procedure, some NHC-catalyzed sulfa-Michael/aldol organocascades were also investigated.
N-heterocyclic carbene catalyzed Michael additions have been revisited with 1,3-dialkyl- or 1,3-diarylimidazol(in)ium-2-carboxylates, that is, NHC·CO2 adducts, as the source of the free NHC catalysts in solution. Using these precatalysts, a number of efficient carba-, sulfa-, and phospha-Michael additions were achieved very conveniently, without the need for an external strong base to generate the NHC by deprotonation of an azolium salt. To further expand the scope of the procedure, some NHC-catalyzed sulfa-Michael/aldol organocascades were also investigated.
“…These are synthesized , under the conditions described for the preparation of aziridines from the corresponding sulfoxides in the presence of SESNIPh 13 and a copper catalyst (eq 14). …”
Section: 32 Synthesis Of Ses Sulfoximinesmentioning
group will be studied before presenting polymer-supported SES groups.
SES−Cl in Synthesis
Synthesis of Sulfonyl ChlorideThe free-radical addition 1 (Scheme 2) of sodium bisulfite on the double bond of vinyltrimethylsilane 1 catalyzed by tert-butyl perbenzoate provided the sulfonate salt 2 which is currently commercially available. This compound was directly transformed into sulfonyl chloride 3 (SES-Cl) by the action of phosphorus pentachloride, 1 thionyl chloride, 6 or sulfuryl chloride. 7 SES-Cl is a distillable liquid (bp ) 60°C/0.1 mmHg) which can be stored at room temperature.
Protection of AminesThe formation of sulfonamide 4 is usually carried out at low temperatures by reaction of the amine with an excess of SES-Cl 3 in the presence of triethylamine (eq 2, Table 1). In the case of aromatic or heterocyclic amines, sodium hydride is instead used as a base.The simple and general synthesis of N-SES amino acids 25,26 should be noted: it starts from the corresponding salt using a temporary trimethylsilane protection on the carboxylic acid function, followed by reaction with SES-Cl (Scheme 3).
“…These are synthesized 92,93 under the conditions described for the preparation of aziridines from the corresponding sulfoxides in the presence of SESNdIPh 13 and a copper catalyst (eq 14).…”
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