A method for asymmetric and site selective annulations at the γ and γ′ positions of cyclic 2‐enones with α,β‐unsaturated aldehydes has been developed. The organocatalysed [3+3]‐annulations proceed with high levels of regio‐, diastereo‐, and enantioselectivity, affording a series of high value fused carbocycles. Further elaboration gave key lactones (both bridged and fused).
The present disclosure relates to a class of pyrimidine derivatives having immunomodulating properties that act via TLR7 which are useful in the treatment of viral infections and cancers.
Selectivity in the cycloadditions of carbonyl ylides with glyoxylates: an approach to the zaragozic acids—squalestatins
作者:David M. Hodgson、James M. Bailey、Carolina Villalonga-Barber、Michael G. B. Drew、Timothy Harrison
DOI:10.1039/b004870o
日期:——
Reaction of diazodiketoester 8 with glyoxylates in the presence of catalytic rhodium(II) acetate generates 6,8-dioxabicyclo[3.2.1]octanes 9 and 11 in good yield. Elaboration of 9 provides a suitable alcohol 25 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 26 of the zaragozic acidsâsqualestatins. More substituted diazodiketoesters 36 and 40 also undergo highly regio- and diastereoselective cycloaddition with glyoxylates to give the cycloadducts 41, 43 and 44.
acrylic esters, obtained by the reaction of nitroalkanes and ethylglyoxalate, are the key building blocks for the immediate synthesis of both the title compounds. In fact, their treatment with titanium trichloride produce the direct conversion to the β-keto esters, while their reaction with sodium boron hydride gives the one-pot synthesis of α,β-unsaturated esters through formal substitution of the
Formal synthesis of (±)-aplykurodinone-1 through an intramolecular Michael addition
作者:Ying Peng、Yongli Sun、Bo Wang、Yi Zhou、Shuangping Huang、Xiaoji Wang
DOI:10.1016/j.tetlet.2019.02.019
日期:2019.3
A concise and straightforward formal synthesis of (±)-aplykurodinone-1, a degraded steroid natural product isolated from sea hare Syphonota geographica is described, based on an intramolecularMichaeladdition. The route also includes an intermolecular Michaeladdition, a Riley selenium dioxide oxidation, and a Krapcho dealkoxycarbonylation. The relative stereochemistries of key intermediates have