Synthesis of the upper fragment of tetronolide

Natural products containing ‘decalin’ motif in microorganisms

“…This kind of biosynthesis related to tetramic acid derivatives was also supported by the group of Hertweck in their discovery of a silent PKS-NRPS hybrid gene cluster and the resulting new pyridine metabolites. 137 YM-215343 (165), isolated from Phoma sp., showed antifungal activities against the pathogenic fungi C. albicans, Cryptococcus neoformans, and Aspergillus fumigatus (MIC values of 2-16 mg mL À1 ) and was cytotoxic against HeLa S3 cells (IC 50 of 3.4 mg mL À1 ). 138 An insect-associated fungus tentatively identied as Cytospora, was found to produce a cholesteryl ester transfer protein inhibitor 166 (IC 50 of 40 mM).…”

“…157 The biosynthetic gene clusters for compounds 180-182 were reported in 2006, 158 2008, 159 To the best of our knowledge, total syntheses of compounds 180- 182 have not yet been reported, even though many syntheses for their aglycones have been achieved and many preparations of the functional intermediates have been accomplished. [162][163][164][165][166][167][168] Enantioselective synthesis of (-)-chlorothricolide, the aglycone of 180, was achieved in 1994 by Roush and Sciotti (Scheme 15). 162,163 Prior to this work, the group of Yoshii reported the chemical synthesis of racemic 24-O-methylchlorothricolide (Scheme 16).…”

“…The aglycon of compound 181, tetronolide, was rst synthesized by the group of Yoshii in 1991. 165,166 Two key steps, the aldol coupling of spirotetronate and a Diels-Alder product decalin system and the internal cyclization, were involved in the construction of the macro-ring as shown in Scheme 17. 165,166 A tandem ketenetrapping [4 + 2] cycloaddition strategy for the total synthesis of (+)-tetronolide was also described.…”

Synthetic Study of Versipelostatin A: Synthesis of the Spirotetronate Unit Starting from Pulegone

“…Herein, we report the efficient synthesis of the spirotetronate unit of versipelostatin A. To date, several synthetic studies of spirotetronate-related compounds, 6,7 such as tetronolide, [8][9][10][11] quartromicin, 12,13 and spirohexenolide, 14 have been reported, and some of these synthetic approaches are currently used for the total synthesis of natural products.…”

Synthesis of the chiral upper fragment of tetronolide

“…Hz, l H , H-6), 3.01 ( t , J 10 1. Hz, l H , H-lo), 3.36 ( s , 3H, OMe), 3.78 (s, 3H, 4-OMe), 4.01 (br s, 2H, H-3'), 4.54 (dd, J 10.1, 2.7 Hz, l H , J 10.4, 1.3 Hz, l H , H-1'), 6.84 (br s, l H , H-€9, 7.35-7.65 (m, 10H, ArH), 9.55 (s, l H , CHO); mass spectrum (electron impact) mlz 576 ( M + ) , 519 ( M + -But, base peak).…”