Diastereoselective Synthesis of γ‑Lactones through Reaction of Enediolates with α,β-Unsaturated Sulfoxonium Salts

Studies of the reaction of lithium enediolates with α,β-unsaturated sulfoxonium salts are described. γ-Lactones were formed in very good to excellent yields (82% → 99% for 11 examples) and with very good to excellent diastereoselectivity (dr >90:10 for 10 examples), favoring the <i>trans</i>-diastereomer

BINAPHANE-Catalyzed Asymmetric Synthesis of <i>trans</i>-β-Lactams from Disubstituted Ketenes and <i>N</i>-Tosyl Arylimines

The development of a BINAPHANE-catalyzed formal [2 + 2]-cycloaddition of disubstituted ketenes and inexpensive <i>N</i>-tosyl arylimines that provides access to a variety of highly substituted β-lactams (16 examples) is described. The BINAPHANE catalytic system displays moderate to excellent enantioselectivity (up to 98% ee) and high diastereoselectivity in most cases, favoring formation of the <i>trans</i>-diastereomer (13 examples with dr ≥ 90:10)

BINAPHANE-Catalyzed Asymmetric Synthesis of <i>trans</i>-β-Lactams from Disubstituted Ketenes and <i>N</i>-Tosyl Arylimines

The development of a BINAPHANE-catalyzed formal [2 + 2]-cycloaddition of disubstituted ketenes and inexpensive <i>N</i>-tosyl arylimines that provides access to a variety of highly substituted β-lactams (16 examples) is described. The BINAPHANE catalytic system displays moderate to excellent enantioselectivity (up to 98% ee) and high diastereoselectivity in most cases, favoring formation of the <i>trans</i>-diastereomer (13 examples with dr ≥ 90:10)

BINAPHANE-Catalyzed Asymmetric Synthesis of <i>trans</i>-β-Lactams from Disubstituted Ketenes and <i>N</i>-Tosyl Arylimines

The development of a BINAPHANE-catalyzed formal [2 + 2]-cycloaddition of disubstituted ketenes and inexpensive <i>N</i>-tosyl arylimines that provides access to a variety of highly substituted β-lactams (16 examples) is described. The BINAPHANE catalytic system displays moderate to excellent enantioselectivity (up to 98% ee) and high diastereoselectivity in most cases, favoring formation of the <i>trans</i>-diastereomer (13 examples with dr ≥ 90:10)

BINAPHANE-Catalyzed Asymmetric Synthesis of <i>trans</i>-β-Lactams from Disubstituted Ketenes and <i>N</i>-Tosyl Arylimines

The development of a BINAPHANE-catalyzed formal [2 + 2]-cycloaddition of disubstituted ketenes and inexpensive <i>N</i>-tosyl arylimines that provides access to a variety of highly substituted β-lactams (16 examples) is described. The BINAPHANE catalytic system displays moderate to excellent enantioselectivity (up to 98% ee) and high diastereoselectivity in most cases, favoring formation of the <i>trans</i>-diastereomer (13 examples with dr ≥ 90:10)

Asymmetric Synthesis of γ‑Lactones through Koga Amine-Controlled Addition of Enediolates to α,β-Unsaturated Sulfoxonium Salts

A chiral Koga amine-controlled asymmetric synthesis of <i>cis</i>-γ-lactones through a formal [3 + 2] cycloaddition of enediolates with α,β-unsaturated sulfoxonium salts is described. The desired structural motif was formed in moderate to good yields (50–71% for 13 examples), with good to very good diastereoselectivity (dr 5:1 to 10:1 for 20 examples), favoring the <i>cis</i>-isomer, and good to excellent enantioselectivity (70–91% ee for 13 examples)

Phosphine-Catalyzed Asymmetric Synthesis of β‑Lactones from Disubstituted Ketenes and Aldehydes

In this article we describe a general catalytic procedure for the formation of β-lactones bearing two stereogenic centers, from disubstituted ketenes and achiral aldehydes. BINAPHANE was found to display excellent enantioselectivity (≥90% ee for eight examples) and good diastereoselectivity (≥90:10 for 13 examples) in catalyzing the formation of β-lactones bearing two stereogenic centers from achiral aldehydes (both aromatic and aliphatic) and alkylarylketenes or dialkylketenes. A preference for formation of the trans diastereomer was observed in these reactions. For those reactions where BINAPHANE failed as a catalyst, tri-<i>n</i>-butylphosphine was found to be an effective achiral nucleophilic catalyst, effecting good yield and diastereoselectivity in racemic β-lactone formation. Evidence for the involvement of phosphonium enolate intermediates in the reaction mechanism was obtained through reaction monitoring by ³¹P NMR spectroscopy and by comparison with previously characterized intermediates observed in the phosphine-catalyzed ketene homodimerization reaction

Diastereoselective Reaction of Sulfoxonium Ylides, Aldehydes and Ketenes: An Approach to <i>trans</i>-γ-Lactones

In this paper, a novel approach to γ-lactones from the reaction of sulfoxonium ylides, aldehydes, and ketenes is described. The new ylide-based method provides access to γ-lactones from disubstituted ketenes, in good yields, and with good diastereoselectivity favoring the <i>trans</i>-diastereomer (11 examples with dr ≥ 82:18, dr up to 92:8)

Diastereoselective Reaction of Sulfoxonium Ylides, Aldehydes and Ketenes: An Approach to <i>trans</i>-γ-Lactones

In this paper, a novel approach to γ-lactones from the reaction of sulfoxonium ylides, aldehydes, and ketenes is described. The new ylide-based method provides access to γ-lactones from disubstituted ketenes, in good yields, and with good diastereoselectivity favoring the <i>trans</i>-diastereomer (11 examples with dr ≥ 82:18, dr up to 92:8)

Asymmetric Synthesis of Deoxypropionate Derivatives via Catalytic Hydrogenolysis of Enantioenriched <i>Z</i>‑Ketene Heterodimers

A diastereoselective approach to deoxypropionate derivatives through Pd/C-catalyzed hydrogenolysis of enantioenriched ketene heterodimers is described. Catalytic hydrogenolysis of the <i>Z</i>-isomer of ketene heterodimers facilitates access to <i>anti</i>-deoxypropionate derivatives (10 examples with dr 7:1 to >20:1). Transfer of chirality from the <i>Z</i>-ketene heterodimer to an acid product was good to excellent in most cases (78–99% ee for 12 examples)