Cyclic Sulfur Ylides Derived from Gleason-Type Chiral Auxiliaries for the Asymmetric Synthesis of Epoxy Amides

Abstract

Gleason-type chiral auxiliaries were used for the synthesis of a novel class of sulfonium salts, obtained via methylation of the sulfide with Meerwein's salt. The salts were reacted with aldehydes under basic conditions to provide epoxy amides, which were reduced to their corresponding epoxy alcohols in excellent enantiomeric excesses. Interestingly, it was feasible to synthesize both enantiomeric epoxy alcohols depending on which of the sulfonium salts, prepared from L-amino acids (6 and 9 from L-valine or 15 and 16 from L-serine) was employed.

Epi-, Epoxy-, and C2-Modified Bengamides: Synthesis and Biological Evaluation

“…As part of a research program engaged in the development of new asymmetric methodologies of epoxidation, we recently designed and synthesized a new class of chiral sulfonium salts, for example, 22 and 23 , which haven proven to be efficient and high-yielding tools for the asymmetric synthesis of epoxy amides, types A and B (Scheme A). Encouraged by these results, we decided to exploit these synthetic tools for the synthesis of various bioactive compounds. , Thus, on the basis of our delineated synthetic strategy for bengamides (Scheme B), which relied on the construction of an oxirane ring and subsequent opening to generate the C2/C3 system, , we applied this novel asymmetric epoxidation for the synthesis of bengamides .…”

Asymmetric Transfer Hydrogenation of α-Substituted-β-Keto Carbonitriles via Dynamic Kinetic Resolution

“…Chiral β-hydroxy carbonitriles are undoubtedly valuable synthons in organic synthesis, since the cyano group is a versatile precursor of amino, carbonyl, and amide groups. − In addition, enantiomerically pure α-substituted-β-hydroxy carbonitrile derivatives such as 1,2-amino alcohol − and 1,3-amino alcohol are highly important and fundamental motifs found in a wide variety of biologically active compounds, , pharmaceuticals, − chiral auxiliaries, , and chiral ligands − in asymmetric synthesis (Figure ). In this regard, the development of efficient method for the synthesis of these compounds is of high significance.…”

Catalytic Asymmetric Epoxidation of Aldehydes with Two VANOL‐Derived Chiral Borate Catalysts

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Ahighly diastereo-and enantioselective method for the epoxidation of aldehydes with a-diazoacetamides has been developed with two different borate ester catalysts of VA NOL. [3][4][5][6][7] At hird method involving the formation of epoxides from the reactions of diazo compounds are not that common and have not been particularly useful. Catalysts generated from BINOL and VA POL are ineffective catalysts.A n application is shown for access to the side-chain of taxol.

The tactical repertoire for the conversion of either an aldehyde or ketone into an epoxide largely consists of two transformations (Scheme 1): 1) the Darzens condensation of an a-halo stabilized carbanion with the ac arbonyl compound, [1,2] 2) the Corey-Chaykovskyr eaction which involves as ulfur ylide as ac arbene surrogate in the synthesis of epoxides.

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“…Catalysts generated from BINOL and VA POL are ineffective catalysts.A n application is shown for access to the side-chain of taxol.The tactical repertoire for the conversion of either an aldehyde or ketone into an epoxide largely consists of two transformations (Scheme 1): 1) the Darzens condensation of an a-halo stabilized carbanion with the ac arbonyl compound, [1,2] 2) the Corey-Chaykovskyr eaction which involves as ulfur ylide as ac arbene surrogate in the synthesis of epoxides. [3][4][5][6][7] At hird method involving the formation of epoxides from the reactions of diazo compounds are not that common and have not been particularly useful. [8][9][10] However, Scheme 1.…”