Rearrangement of Threonine- and Serine-Based N-(3-Phenylprop-2-yn-1-yl) Sulfonamides Yields Chiral Pyrrolidin-3-ones

Lewis-Acid-Catalyzed Reductive Hydroalkoxylation of Propargylic N-Hydroxylamines Gives Stereoselective Access to Isoxazolidines

Lewis-acid-catalyzed 5-endo-dig reductive hydroalkoxylation cascade on propargylic N-hydroxylamine gave expedient, stereoselective access to isoxazolidine derivatives. The developed method provides a new approach toward the synthesis of isoxazolidine, a biologically privileged scaffold. The synthetic potential of the developed methodology was demonstrated by synthesizing 1,3-aminoalcohol, 4-aminotetrahydropyran, and sedamine natural products.

Synthesis of Polycyclic Tetrahydroisoquinolines and Tetrahydrobenzo[d]azepines from Polymer-Supported Allylglycine

Herein, we report a multistep synthesis of polycyclic tetrahydroisoquinolines and tetrahydrobenzo[d]azepines starting from Wang resin-immobilized allylglycine. After sulfonylation with 2/4-nitrobenzenesulfonyl chlorides, Mitsunobu alkylation with various phenylalkynols yielded the corresponding (phenylprop-2-yn-1-yl)-sulfonamides. "Interior" ring-closure enyne metathesis (RCEM) using a Grubbs catalyst second generation (Ru2) yielded functionalized tetrahydroisoquinoline/tetrahydrobenzo[d]azepine intermediates. "East-side" [4 + 2] cycloaddition with representative dienophiles was followed by the "west-side" construction of different heterocycles using various electrophiles to finally furnish a set of novel molecular frameworks bearing fused [6 + 6] or [6 + 7] rings. The developed methodology enables the facile parallel synthesis of novel, pharmacologically promising compounds derived from privileged scaffolds.

Reagent-Based Diversity-Oriented Synthesis of Triazolo[1,5-a][1,4]diazepine Derivatives from Polymer-Supported Homoazidoalanine

Herein, we report the synthesis of skeletally different triazolo[1,5-a][1,4]diazepines starting from immobilized homoazidoalanine. After sulfonylation with 2/4-nitrobenzenesulfonyl chlorides and Mitsunobu alkylation with various alkynols, the corresponding N-substituted nitrobenzenesulfonamides were obtained. Their catalyst-free Huisgen cycloaddition provided immobilized and functionalized triazolo[1,5-a][1,4]diazepines as the key intermediates for further modification. Using the concept of diversity-oriented, reagent-based synthesis, the key intermediates were subsequently converted to heterocycles bearing [5 + 7 + 5], [5 + 7 + 6], and [5 + 7 + 7] scaffolds. Furthermore, the synthesis of spirocyclic triazolodiazepines was developed.