β-Amino Sulfoxides Research Articles

Origins and applications of stereoselective sulfenate anion alkylation reactions

Selected sulfenate anions can be alkylated with diastereoselectivities near 9:1 when there is appropriately positioned carbon chirality in the sulfenate structure or in the alkylation electrophile. Both protocols represent a conceptually different approach to β-amino sulfoxides. When vinylic β-amino sulfoxides are cyclized, thiomorpholine S-oxides result, and substrate control over the stereochemistry of alkyl substituents was found. This finding facilitates the synthesis of cis and trans dialkylpyrrolidines, known ant venom alkaloids. A computational model is demonstrated to account for some of the diastereoselection results. The importance of intramolecular interactions of sulfenate constituent atoms with pendent substituents is established.

Stereodivergent Access to Cis- and Trans-3,5-Disubstituted 1,4-Thiazane 1-Oxides by Cyclization of Homochiral β-Amino Sulfoxides and Sulfones. The Preparation of Isomeric Ant Venom Alkaloids

Intramolecular conjugate additions of homochiral (E)-1-alkenyl 2-aminoalkyl sulfoxides and sulfones were investigated. The relative position of the 3,5-substituents of the resulting 1,4-thiazane oxides was found to be dependent on the oxidation state of the sulfur atom, demonstrating a simple and highly stereodivergent synthetic protocol. Selected cis- and trans-3,5-disubstituted 1,4-thiazane dioxides were converted to cis- and trans-2,5-disubstituted pyrrolidines, known ant venom alkaloids.

ChemInform Abstract: Sulfenate Substitution as a Complement and Alternative to Sulfoxidation in the Diastereoselective Preparation of Chiral β‐Substituted β‐Amino Sulfoxides.

AbstractCoupling of arene‐, alkene‐, and alkanesulfenate anions with chiral β‐amino iodides is found to provide a useful method to prepare optically active β‐amino sulfoxides.

Sulfenate Substitution as a Complement and Alternative to Sulfoxidation in the Diastereoselective Preparation of Chiral β-Substituted β-Amino Sulfoxides

Building from a previous communication, the reaction of sulfenate anions with chiral N-Boc-protected β-substituted β-amino iodides was evaluated as a conceptually different synthetic approach to chiral β-substituted β-amino sulfoxides. Using arenesulfenates, yields typically ranged from 71% to 92%, and dr's were often near 9:1. Alkanesulfenates proved less reactive, delivering lower yields and dr's. 1-Alkenesulfenates demonstrated high reactivity, returning chemical yields of 60-86% and dr's often close to 9:1 and as high as 95:5. (S)-β-Amino iodide electrophiles yielded (R(S),S(C))-β-amino sulfoxides, whereas (R)-amino iodides afford (S(S),R(C))-β-amino sulfoxides. The absolute configuration of the products makes the sulfenate protocol complementary to other existing preparations, including the commonly employed sulfoxidation of β-amino sulfides. The reactivity of N-Boc-protected 2-benzyl-2-aminoethyl iodide was found to be superior to the less sterically encumbered n-butyl iodide. A transition state model is proposed to account for the stereochemistry of the products and also for the high reactivity of the electrophile. Overall, the chemistry represents a new means of introducing sulfur stereogenicity in a molecule.

The Diastereoselective Alkylation of Arenesulfenate Anions Using Homochiral Electrophiles

A series of Boc-protected β-amino sulfoxides were prepared by the reaction of arenesulfenate anions with chiral Boc-protected β-amino iodides. The stereoselective substitution reaction is believed to arise through precoordination of the sulfenate counterion with the nitrogen lone pair of the electrophile.

Novel Approach for Asymmetric Synthesis of Fluorinated β‐Amino Sulfones and Allylic Amines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

ChemInform Abstract: Additions of Enantiopure α‐Sulfinyl Carbanions to (S)‐N‐Sulfinimines: Asymmetric Synthesis of β‐Amino Sulfoxides and β‐Amino Alcohols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Structural Investigations of Novel Palladium(II) and Rhodium(I) Complexes Containing Chiral Ligands with a Stereogenic Sulfur Donor, Such As β-Amino Sulfoxides and C2-Symmetric Bis-Sulfoxides1

Two kinds of new optically active chelating ligands bearing a chiral sulfinyl functionality, namely the 3,4-bis-(p-tolylsulfinyl)hexanes 4 and the N-mono- and N,N-disubstituted β-p-tolylsulfinyl ethylamines 5 and 2, have been synthesized and their coordination chemistry with Pd(II) and Rh(I) metals has been studied in detail. Complexes formed with ligands 4 featured a homocoordination between the two sulfur donors and the metal atom, in solution as well as in the solid state, as demonstrated by X-ray diffraction of cis-dichloro[3,4-bis-(p-tolylsulfinyl)hexane]palladium(II) ((3R,4R,RS,RS)-7), in which the ligand shows a C2 symmetry. Complexes formed with ligands 2 and 5 showed a heterocoordination of the metal by the sulfur and the nitrogen donors, as confirmed by X-ray diffraction of cis-dichloro[N,N-dimethyl-2-(p-tolylsulfinyl)ethylamine]palladium(II) ((R)-6). All nine complexes 6−11, displaying a monomeric structure, have been synthesized and completely characterized in the solid state (IR, MS-FAB) as w...

Chiral β-amino sulfoxides. Synthesis, configurational assignment and conformational analysis based on X-ray, CD, 1H NMR and theoretical calculations

Enantiomerically pure u and l β-amino sulfoxides have been easily obtained from the respective homochiral α-amino alcohols. The absolute configuration at the created stereogenic centre was assigned by CD spectra and by X-ray analysis. Conformational analysis of the title compounds was carried out using quantum chemical energy-geometry optimization. Thus established conformational behavior explained the strongly configuration dependent NMR spectral patterns observed for the u and l diastereomers.

Highly diastereoselective reduction of chiral β-imino sulfoxides to the corresponding β-amino sulfoxides

The hydride reduction of chiral β-imino sulfoxides with 1-benzyl-1-azonia-4-azabicyclo[2, 2, 2]octane tetrahydroborate (BAAOTB) to the corresponding β-amino sulfoxides is described.

Synthesis of Homochiral N-Protected β-Amino Sulfoxides from α-Amino Alcohols

Synthesis of Homochiral N-Protected β-Amino Sulfoxides from α-Amino Alcohols

Stereoselective Reduction of Enamino Sulfoxides

Abstract Enamino sulfoxides, p-TolS(O)CH=C(NR1R2)R (where R1 = alkyl, R2 = H or alkyl), were reduced with lithium tri(s-butyl)borohydride or borane·THF, respectively, to give β-amino sulfoxides of R*,R* configuration with high stereoselectivity.