Synthesis of 4a-carba-β-l-lyxofuranose, 4a-carba-β-l-arabinofuranose and 2,2,5-trimethyl-3a,6a-dihydro-cyclopenta[1,3]dioxol-4-one using Mn/CrCl3 mediated domino reactions and ring closing metathesis

A common method for the synthesis of 4a-carba-β-l-lyxofuranose and 4a-carba-β-l-arabinofuranose from d-mannose and 2,2,5-trimethyl-3a,6a-dihydro-cyclopenta1,3]dioxol-4-one from d-ribose is described using catalytic Nozaki-Hiyama-Kishi (NHK) conditions and ring closing metathesis (RCM). In this transformation, ω-deoxy-ω-iodo manno/ribo furanoside undergoes reductive elimination in the presence of Mn/CrCl₃ to give the corresponding olefin-aldehyde which was trapped by nucleophile under the same conditions to afford the desired diolefinic species. The ring closing metathesis reaction on these diolefinic species with Grubbs second generation catalyst produced the required carbocycles.