Masahiro Miyazawa

A new preparation of 2,5-dihydro-1-benzoxepins using Mitsunobu cyclization, and the synthesis of natural radulanins

Abstract Mitsunobu cyclization of o -[4-hydroxy-3-methyl-2( Z )-butenyl]phenol 2a effected selective seven-membered cyclization to give 3-methyl-2,5-dihydro-1-benoxepin 1a . Using this procedure, natural radulanin A and radulanin A methyl ether were synthesized effectively.

Palladium(II)-catalyzed stereocontrolled cyclization via hemiacetal intermediates: Total synthesis of 5-epi-prelactone C

Palladium(II)-catalyzed cyclization of 3,7-dihydroxy-4-methyl-5-octenal derivative was carried out to give 2,3,4,6-tetrasubstituted tetrahydropyran with stereoselective 1,3-chirality transfer in net retention of stereochemistry. The cyclized product was converted into 5-epi-prelactone C.

Regioselective cyclization of m-acylaryl 1,1-dimethylpropargyl ethers giving 5-acyl-2,2-dimethyl-2H-chromenes

Abstract Thermal cyclization of some m -acylaryl 1,1-dimethylpropargyl ethers ( 1a – f ) effected regioselective ortho cyclization giving the corresponding 5-acyl-2,2-dimethyl-2 H -chromenes ( 2a – f )