The synthesis of novel adamantane-like cage compounds consisting of phosphorus, sulfur, and carbon atoms was developed. We examined the reaction of a variety of acetophenone derivatives with P4S10 in refluxing benzene. A novel noradamantane-like cage compound was also synthesized, when the reaction of 2’-methoxyacetophenone with P4S10 was performed in refluxing toluene. In addition, by using the adamantane-like cage compound, 4,4’-dimethoxybenzophenone and N,N-dimethylbenzamide were successfully transformed into the corresponding thioketone (98%) and benzothioamide (89%), respectively.Download high-res image (222KB)Download full-size image

•Regioselective elimination of a vicinal bis-triflate having an adjacent ether oxygen functional group has been developed.•An unusual combination of n-BuLi/dichloromethane led to the high selectivity of elimination reaction.•The key involved the electron-withdrawing inductive effect of an adjacent ether oxygen functional group.Regioselective elimination of a vicinal bis-triflate having an adjacent ether oxygen functional group has been developed. Considered in the context of our studies of the regioselective elimination of vicinal dibromide, the key to the mechanism involves the electron-withdrawing inductive effect of the neighboring oxygen functional group. Aliphatic vinyl triflate was shown to be effective in Suzuki–Miyaura cross coupling compared with corresponding aliphatic vinyl bromide.Download high-res image (71KB)Download full-size image

•Total synthesis of a quinolinone alkaloid haplacutine C is achieved.•The keys are the intramolecular aldol condensation and the Stille coupling.•The 4-O-protected-quinolines are utilized as the synthetic equivalents of 4-quinolinone skeletons.A total synthesis of haplacutine C has been achieved. The synthetic key features were the intramolecular aldol condensation for construction of the 4-quinolinone skeleton and the Stille coupling for elongation of the dienol side chain. In addition, the 4-O-protected-quinolines were also utilized as the synthetic equivalents of 4-quinolinone at the stage of side chain transformation.

The first total synthesis of aplysinoplide B has been achieved. The synthetic highlight of our approach includes sp2–sp3 Suzuki–Miyaura cross coupling of a vinyl bromide with an alkyl 9-BBN derivative. The vinyl bromide was efficiently synthesized from the disubstituted Z-alkene utilizing a one-pot regioselective bromination. Through the synthetic studies, the absolute stereochemistry at the C4 position of naturally occurring aplysinoplide B was established as an R configuration.

The first total synthesis of (−)-5,6-seco-germacrane lactone has been achieved. The synthetic highlight of our approach includes sp2–sp3 Suzuki–Miyaura cross coupling of a vinyl bromide and an alkyl 9-BBN derivative. The vinyl bromide was easily prepared from the chiral lactonic building block using a one-pot regioselective bromination. The asymmetric carbon center of the alkyl boron compound was formed using the zirconium-catalyzed carbomagnesation of 2,5-dihydrofuran.