Synthesis of Sterically-Crowded Olefins, gem-Dihaloalkenes, Butatrienes, and Thioketenes through the Reaction of Substituted Bornane-2-thiones or Bornane-2-selones with Conventional Carbenes or Metal Carbenoids

Abstract

Reaction of highly-substituted bornane-2-selones with a diazoalkane in the presence of either Rh 2 (OAc) 4 or CuCl formed sterically-crowded exo-methylenic products, and similar treatment of the thiones or selones with dihalocarbenes or a propadienylidene carbene also formed dihaloalkenes, butatrienes, and thioketenes. All these reactions were assumed to proceed through a pathway involving the in situ formation and subsequent ring closure of chalcogenocarbonyl ylides.

Reactions of thiocarbonyl compounds with electrophilic and nucleophilic carbenes as well as with their metal complexes

“…A study on the reactions of sterically crowded bornane-2-thiones of type 105 with dichloro-and dibromocarbene generated from different precursors was reported recently [47]. Depending on the reaction conditions, the 2-methylidene derivative 106 or thioketene 107 and its dimer were isolated from the reaction mixture (Figure 1).…”

Synthesis of Functionalized Chiral Imidazole Derivatives Based on a Bornane Skeleton Bearing a Sterically Crowded Spirocyclic Substituent at the C-3 Position

“…Sterically crowded camphor derivatives 1a-b bearing a spirocyclic substituent at the C-3 position were at first prepared from d -camphor according to the reported method, 23 -27 28,29 and ketones 1a-b were converted into the corresponding thiones 2a-b by treating with Lawesson’s reagent according to our previous reports. 23 Subsequently, thiones 2a-b were converted into the corresponding 10-bromobornane-2-thiones 3a-b (X = Br) in almost quantitative yields by treating with bromine (1.1 mol amt.)…”