Solid phase ring-closing metathesis: Cyclization/cleavage approach towards a seven membered cycloolefin

Solid‐Phase Synthesis of Heterocyclic Systems (Heterocycles Containing One Heteroatom)

“…Resin-bound 2-(azaallyl) stannanes 34 so obtained are transmetalated (n-BuLi), in the presence of electron-rich alkenes, to furnish pyrrolidine anions 37 which may be alkylated upon subsequent addition of an electrophile. Six fully substituted pyrrolidines (38,39) were prepared in 32-50% overall isolated yield.…”

“…15-22.17) [36][37][38]. Metathesis reactions generally proceed in good yield with minimal intermolecular cross-linking.…”

Stereoselective Solid-Phase Synthesis of -Lactams—A Novel Cyclization/Cleavage Step towards 1-Oxacephams

“…Commercially available Wang resin 6 (Rapp polymer, 1.13 mmol of OH per gram of resin) was treated with trichloroacetonitrile and DBU and transformed into the Wang trichloroacetimidate resin 7, which was recently shown to be a polymer-bound benzylating reagent and capable of immobilizing alcohols under mild conditions. [11] The resin 7 was coupled with the chiral methyl (S)-3-hydroxybutyrate (8) or with the 1,2-Oisopropylidene-5-O-pivaloyl-a-d-xylofuranose (9) in the presence of catalytic amounts of BF 3´E t 2 O in CH 2 Cl 2 /cyclohexane (1/1) for 5 min at room temperature according to the procedure of Hanessian and Xie [11] to afford 10 and 11, respectively. The IR spectra of 10 and 11 showed the absence of the strong CN stretching band at 1664 cm…”

“…[8] The metathesis for the synthesis of cycloolefins [9] and formation of macrocyclic lactones by a intramolecular ketophosphonate ± aldehyde condensation reaction have been reported recently. [10] The high purity of the detached final products is an important advantage of the well designed cyclization/cleavage strategy because only the required precursor of the target molecule undergoes cyclization.…”

“…[3] The development of new [9] An aqueous solution of iron(iii) chloride was treated with salicylaldoxime in EtOH and neutralized with one equivalent of base to give a red-brown precipitate. Washing this product with hexane removed excess ligand, and subsequent extraction with CH 2 Cl 2 followed by solvent evaporation in vacuo yielded a dark brown solid.…”