General and Chemoselective Bisphosphonylation of Secondary and Tertiary Amides

With Tf₂O as the activation reagent, a mild and general method has been developed for the bisphosphonylation of both secondary and tertiary amides. The protocol is highly efficient and chemoselective, and it tolerates a number of sensitive functional groups such as cyano, ester, and aldehyde groups

A Photochemical Route to 3- and 4‑Hydroxy Derivatives of 2‑Aminocyclo­butane-1-carboxylic Acid with an <i>all-cis</i> Geometry

Short gram-scale syntheses of both enantiomers of 2-amino-3-hydroxy­cyclo­butane-1-carboxylic acid and of 2-amino-4-hydroxy­cyclo­butane­carboxylic acid with an <i>all-cis</i> geometry are described. The sequences feature highly <i>endo</i>-selective [2 + 2]-photocycloaddition reactions followed by fully regioselective ring opening/Hofmann rearrangement/nitrogen protection, in a consecutive or one-pot protocol, followed by efficient resolution using a chiral oxazolidinone