title: Simple reagents for direct halonium-induced polyene cyclizations.
abstract: Although there are many reagent combinations that can initiate polyene cyclizations, simple electrophilic halogen sources have not yet proven broadly effective as promoters of such processes. Herein is described a readily prepared and stable class of reagents capable of effecting such transformations for a wide range of electron-rich and -deficient terpenes derived from geraniol, farnesol, and nerol, thereby enabling the effective synthesis of a diverse array of complex chlorine-, bromine-, and iodine-containing polycyclic frameworks. Efforts to date have led to the first racemic laboratory total synthesis and structural revision of the anti-HIV natural product peyssonol A as well as an efficient and concise inaugural total synthesis of peyssonoic acid A. They have also permitted formal racemic total syntheses of aplysin-20, loliolide, K-76, and stemodin to be achieved through routes that are typically shorter, higher-yielding, and more environmentally conscious than previous efforts. Preliminary attempts to use chiral forms of the reagent class for enantioselective alkene halogenation are also described.
authors.affiliation: Department of Chemistry, Columbia University, Havemeyer Hall, 3000 Broadway, New York, New York 10027, USA. sas2197@columbia.edu
authors.forename: Scott A
authors.initials: SA
authors.lastname: Snyder
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Treitler
authors.forename: Alexandria P
authors.initials: AP
authors.lastname: Brucks
mesh_terms: D003500:Cyclization; D006219:Halogens / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry*; D011090:Polyenes / Q000737:chemistry*
chemical_list: D006219:Halogens; D007202:Indicators and Reagents; D011090:Polyenes