Stereoselective Total Synthesis of (+)-Brevipolide H from d-Galactal

Abstract

The efficient and concise synthesis of cytotoxic 5, 6-dihydro-α-pyrone (+)-brevipolide H has been accomplished in 12 long linear steps with 8.65% overall yield from readily available chiral synthons, D-galactal and L-ethyl lactate. The features of this synthesis are highly diastereoselective Simmons-Smith cyclopropanation and carbohydrate-based chiron approach to rapid access to key 5, 6-dihydro-α-pyrone skeleton.

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

“…We first investigated the reaction outcome using a set of bases in the presence of Pd(OAc) 2 as the catalyst (5 mol %) in DMA at 150 °C. This catalyst precursor is known to efficiently promote the direct coupling of 5-membered ring heteroarenes with aryl halides [ 25 ]. Cs 2 CO 3 and K 2 CO 3 proved to be totally inefficient bases, while acetate bases gave the desired product 1 but only in trace amounts (Table, entries 1–5).…”

“…We have previously described the reaction of 1,8-dibromonaphthalene with some heteroarenes such as 2-methylthiophene in the presence of a palladium catalyst for the synthesis of acenaphtho[1,2- d ]thiophenes [ 25 ]. In these reactions, the C–H bonds at the C2 and C3 positions of the thienyl unit were functionalized.…”

Bioinspired synthesis and biological evaluation of ent-protulactones A and B

“…In particular, to the best of our knowledge, neither the total synthesis nor the biological activity of protulactone B ( 2 ) has been reported so far. In continuation of our efforts toward the total synthesis of various complex natural products based on carbohydrate skeletons, 9 herein we disclose the bioinspired and stereoselective synthesis of protulactones A and B using readily available methyl α- d -mannopyranoside as a chiral pool, along with their effects on the proliferation of selected tumor cell lines (MCF-7 and Capan 2).…”