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TMSOTf-catalyzed intramolecular condensation for catechin and epicatechin units are described. A potential electrophile and a nucleophile were connected with diester linkers and TMSOTf-catalyzed condensation was examined. In comparison with intermolecular catechin and catechin condensation, the intramolecular condensation required high reaction temperature and reversed 3,4-cis product was obtained. The condensed product was transformed into the natural 3,4-cis (+)-catechin-(4β→8)-(+)-catechin dimer.

We developed a facile method of enzyme-mediated conversion of 6-tuliposide to α-methylene-γ-butyrolactone (tulipalin). We used a tuliposide-converting enzyme for the conversion of 6-tuliposides extracted from tulip tissues into the corresponding tulipalins in high yields within 2 h at pH 7.0. The resulting tulipalins were selectively extracted by using several organic solvents.

We have succeeded in one-pot preparation of perfluoroimidates at −78 °C by employing the dehydration of perfluoroamide under the “activated” dimethyl sulfoxide (DMSO) species followed by in situ nitrile trapping with alcohols. MPM and DMPM perfluoroimidates can be used to protect alcohols in place of the trichloroacetimidate with excellent chemical properties and in comparable yields.

In order to establish a mild conversion method of primary amides to nitriles, various types of carboxamides were treated under Swern oxidation conditions, (COCl)2-DMSO and Et3N, as a dehydrating agent to obtain desired nitriles in 75–96% yields.

The first total synthesis of 16-membered tetraene macrolide antibiotic hydrolidin, a potent and relatively specific inhibitor of the vacuolar ATPases, has been achieved, incorporating macrolactonization by the modified Yamaguchi method and fragment assembly aldol reaction to establish the C17-C18 bond as key steps.

Toward the first total synthesis of 16-membered macrolide antibiotic hygrolidin, the C1C17 seco-acid fragment and the C18C25 masked hemiacetal subunit as potential precursors have been synthesized in enantiomerically homogeneous forms.

Computer-aided conformational analyses are successfully applied to the synthesis of a key intermediary 18-membered lactone of tedanolide (1). The design of a seco-acid derivative based on computation in order to achieve its efficient macro-lactonization is described.

The key synthetic intermediate of maridonolides ( 2 ) has two easily detectable conformational isomers in solution. The conformational analysis of the 16-membered epoxyenone ring and the effect of conformation on reactivity in the reduction of the C9 carbony group are described.

In order to establish a mild protection method for hydroxy functions with a MPM (4-methoxybenzyl) group, various types of hydroxy compounds were treated with MPM trichloroacetimidate in the presence of an acid catalyst. A catalytic amount (0.3 mol %) of trifluoromethanesulfonic acid was most effective and the reaction was completed within 40 min at room temperature even for highly sterically hindered hydroxy groups.