The radical cyclization between aliphatic acyclic esters and alkenes was achieved unprecedentedly in the presence of allylsamarium bromide with HMPA and H(2)O as additives. The cascade radical cyclization-ring-opening-anionic cyclization allowed facile and efficient access to 2-(2-hydroxyalkyl)cyclopropanols from readily available materials.

Polyketide antibiotics bearing skipped polyols represent a synthetic challenge. A SiCl4‐promoted oxonia‐Cope rearrangement of syn,syn‐2‐vinyl‐1,3‐diols was developed to forge an array of 1,5‐pentenediols, thus providing versatile motifs for the preparation of 1,2,3,5‐stereoarrays in a highly stereoselective manner. Further exploration with Sn(OTf)2 realized the rearrangement of a cross‐aldehyde which tactically warrants the utility of the current approach to access complex polyketides. The origin of high stereoselectivity is attributed to a chairlike anti‐conformation of the oxonium ion intermediate.

3-Aryl-1,2,4-benzotriazines were conveniently prepared in moderate to good yields from 1,l-bis(benzotriazol-1yl)methylarenes with allylsamarium bromide/hexamethylphosphramide (allylSmBr/HMPA). Preliminary results indicate that HMPA may enhance the reducing ability as well as prohibit the nucleophicility of allylSmBr, thus making allylSmBr/HMPA as a promising single-electron transfer (SET) reagent.Keywords benzotriazines, samarium, allyl bromide, hexamethylphosphramide (HMPA), reduction 2f, 65 (50) 3f, 26 (32) Reactivity of AllylSmBr/HMPA: Facile Synthesis of 3-Aryl-1,2,4-benzotriazinesChin.