Cyclopropyl epoxides. Reactions of some αβ-dibromoketones with dimethyloxosulphonium methylide

Abstract

2,3-Dibromo-3-phenylpropiophenones eliminated both bromine and hydrogen bromide on reaction with dimethyloxosulphonium methylide (DMOSM) ; the resulting ap-unsaturated ketones formed cyclopropyl ketones which, when suitably substituted, continued to react with DMOSM, forming a variety of heterocyclic products. A contiguous cyclopropyl epoxide underwent ring-opening oxymercuriation with mercuric acetate via 5-oxypent-2-en-1 -01s. A cyclopropylcyclopropane analogue of the epoxide was stable at 300 "C.

Some reactions of carbenoids with chromone-2-carboxylic esters

“…Thus compounds (3a) and (3b) give rise respectively to the products (4a)-(7a) and (4b)-(6b) as summarised in the Table . The stereochemistry of the annelated cyclopropane ring followed from the coupling constants of the protons HA and HB in compounds (4), (5), and (6). In (4) and (6) J A B is 7 Hz whereas in ( 5 ) it is 11 Hz, the latter being consistent with a cis arrangement of the cyclopropane protons. Thus (5) has endu-and (4) and (6) have exo-acetyl substituents.…”

“…The observed products (4)- (6) probably arise from an initial conjugate addition of the anion of chloroacetone to the pyrone ring, followed by expulsion of chloride with consequent cyclopropane ring formation (Scheme 1). The reaction is in fact analogous to the Darzens glycidic ester condensation.2u Related cyclopropanation reactions of enones are aIso known (for example see ref.…”

Synthesis of (Het)aryl 2-(2-hydroxyaryl)cyclopropyl Ketones

“…Moreover, compound 2a was formed in trace amounts only, when all steps of process occurred at room Despite the promising reactivity and bioactivity of 2-hydroxyaryl-substituted cyclopropanes, their investigation is restricted by the absence of simple and efficient methods for their synthesis. In particular, the preparation of the corresponding cyclopropane-1,1-diesters requires protection of the phenolic oxygen [41,50], while the Corey-Chaykovsky cyclopropanation of easily available 2-hydroxychalcones produced a variety of products [56][57][58][59][60]. This presumably resulted from the highly activating effect of ortho-hydroxy group [50,60] on three-membered ring opening as well as the possible involvement of the nucleophilic phenoxy moiety into diverse transformations of 2-hydroxyaryl-derived D-A cyclopropanes.…”

“…In particular, the preparation of the corresponding cyclopropane-1,1-diesters requires protection of the phenolic oxygen [41,50], while the Corey-Chaykovsky cyclopropanation of easily available 2-hydroxychalcones produced a variety of products [56][57][58][59][60]. This presumably resulted from the highly activating effect of ortho-hydroxy group [50,60] on three-membered ring opening as well as the possible involvement of the nucleophilic phenoxy moiety into diverse transformations of 2-hydroxyaryl-derived D-A cyclopropanes. We report here the efficient procedure for the preparation of 1-acyl-2-(2-hydroxyaryl)cyclopropanes as potent bioactive compounds and promising building blocks for the synthesis of various acyclic, alicyclic and heterocyclic compounds.…”