Bridging of macrodithionolactones to bicyclic systems. Synthesis and modeling of oxapolycyclic frameworks

cis-3,4-Dichlorocyclobutene as a Versatile Synthon in Organic Synthesis. Rapid Entry into Complex Polycyclic Systems with Remarkably Stereospecific Reactions We thank Drs. D. H. Huang and G. Siuzdak for their assistance with NMR spectroscopy and mass spectrometry, respectively. This work was financially supported by the National Institutes of Health (USA) and The Skaggs Institute for Chemical Biology, a postdoctoral fellowship from the Skaggs Institute for Research (to V.G.), and grants from Abbott, Amgen,

“…Hydroxytetrahydropyran 5 was prepared in enantiomerically pure form from 6 by a modification of a previously published sequence. [5] Thus, benzylidine formation followed by regioselective reduction with DIBAL-H, Swern oxidation, Wittig olefination, and DDQ-induced deprotection converted 6 into 5 in good overall yield (Scheme 2). …”

“…[4] The addition of Grignard reagents to 9 sometimes gave complex mixtures, so that in general the (hydroxymethyl)oxazolines 7 were preferentially synthesized by means of the imidate route. [5] The modular nature of 2 with its three permutable structural units (R 1 , R 2 , and the P-substituents) is an attractive feature of these ligands. Especially the selection of the R 1 group, which is derived from a carboxylic acid, is essentially unlimited.…”

Total Synthesis of Brevetoxin A: Part 1: First Generation Strategy and Construction of BCD Ring System

“…The synthesis commences with previously prepared [52] diol 63 which was selectively protected at the primary position as silyl ether 64 (TBDPSCl, imidazole, 94 % yield). Upon treatment with mCPBA, hydroxyl-directed epoxidation of 64 generated desired epoxide 65 (75 % yield).…”

Synthesis of Novel Tetrahydropyran‐Based Dipeptide Isosters by Overman Rearrangement of 2,3‐Didehydroglycosides

“…Application of triethylsilane as the incoming nucleophile in the Lewis acid-mediated Ferrier rearrangement of 1 furnished derivative 17 in 96% yield. Conversion of 17 into 20 [23] and ensuing transformations into the target dipeptide isoster 6 went uneventfully (18% overall yield based on 1), following the sequence of transformations as outlined for the synthesis of 5.…”