Copper‐Catalysed Double O‐Arylation for Enantioselective Synthesis of oxa‐Spirocycles

Abstract

A copper-catalysed double O-aylation for enantioselective formation of chiral oxa-spirocycles is described. The method is based on a stepwise process and afforded chiral oxa-spirocycles with good yields and moderate to high enantioselectivities.

Copper‐Catalyzed Dynamic Kinetic C−P Cross‐Coupling/Cyclization for the Concise Asymmetric Synthesis of Six‐, Seven‐ and Eight‐MemberedP‐Stereogenic Phosphorus Heterocycles

“…The classic ligands PyBox L2 and Box L3 were screened, but they had poor enantioselectivities (Table 1, entries 2 and 3). N , N ′‐Dimethyl diamine ligands have been employed to enhance the efficiency of copper‐catalyzed reactions [17] and chiral ethylenediamine ligands have exhibited tremendous success in various asymmetric catalysis [11c, 18] . A series of chiral ethylenediamine ligands were screened, among which L6 gave the best result with 96 % ee and 96 % yield (Table 1, entries 4–8).…”

Base-promoted cyclization ofortho-hydroxyacetophenones within situgenerated cyclopropenes: diastereoselective access to spirobenzo[b]oxepines and related precursors

“…Although there is incredible advancement in benzoxepine synthesis, stereoselective access to biologically attractive spirobenzo[ b ]oxepines with a carbocyclic or heterocyclic scaffold has met with limited success. 19 c ,20,21 For example, Du et al recently disclosed an appealing domino strategy for the diastereoselective construction of spirobenzo[ b ]oxepines bearing an oxindole moiety via a DABCO-catalyzed [3 + 4] annulation of MBH carbonates of isatins with ortho -quinone methides as 4C synthons (Scheme 1a). 19 c…”

A Modular Approach for the Palladium-Catalyzed Synthesis of Bis-heterocyclic Spirocycles

“…Cs 2 CO 3 in toluene at 100 °C gave the optimal yield of spiro[benzofuran-3,3′-chromane] (2a) (88% NMR yield, 80% isolated yield). This strategy proved to be convenient to access spiro[benzofuran-3,3′-chromane]s, as previous methods to generate these compounds required sequential intramolecular C−O cross-couplings 26 or a multistep radical cyclization−reduction sequence. 27 It was essential to obtain >95% conversion of the starting material, as separation from the product proved to be extremely difficult.…”