Stereoselective Synthesis of Bicyclo[6.1.0]nonene Precursors of the Bioorthogonal Reagents s-TCO and BCN
作者:Jessica G. K. O’Brien、Srinivasa R. Chintala、Joseph M. Fox
DOI:10.1021/acs.joc.7b02329
日期:2018.7.20
The cyclooctyne BCN and the trans-cyclooctene s-TCO are widely used in bioorthogonal chemistry. A bottleneck for their synthesis had been a poorly selective cyclopropanation with ethyl diazoacetate. Here, we describe that low catalyst loadings (0.27 mol %) of Rh2(S-BHTL)4 provide the BCN precursor with 79:21 syn/anti selectivity. The synthesis of the s-TCO precursor was best achieved through a sequence
Large-Scale Flow Photochemical Synthesis of Functionalized trans-Cyclooctenes Using Sulfonated Silica Gel
作者:Ampofo Darko、Joseph Fox、Samantha Boyd
DOI:10.1055/s-0037-1610240
日期:2018.12
Functionalized trans-cyclooctenes are useful bioorthogonal reagents that are typically prepared using a flow photoisomerization method in which the product is captured by AgNO3 on silica gel. While this method is effective, the leaching of silver can be problematic when scaling up syntheses. It is shown here that Ag(I) immobilized on tosic silica gel can be used to capture trans-cyclooctene products at
Preparation of diastereomerically pure 9-carboxybicyclo[6.1.0]nonane derivatives
作者:Eckehard Volker Dehmlow、Olaf Pl�ckebaum
DOI:10.1002/prac.19963380161
日期:——
Reactions of cyclooctene (1) with dibromocyanoacetic esters and copper(I) bromide give (8-10) : 1 mixtures of isomers (2, 3), not stereochemically pure compounds as reported by others. The stereochemistry is elucidated by independent synthesis of one diastereomer (3a). Carbenoid addition of alkoxycarbonylmethylene to 1 and 1,5-cyclooctadiene leads also to exo/endo adduct mixtures. Methods are developed to generate diastereomerically pure compounds (exo-7a, exo-8, endo-9, exo-10, endo-10) from these. Endo esters of this series undergo very facile base catalyzed epimerization.
Copper-Free Click Reaction Sequence: A Chemoselective Layer-by-Layer Approach
作者:Jannick Meinecke、Ulrich Koert
DOI:10.1021/acs.orglett.9b02891
日期:2019.9.20
ligation of dual clickable building blocks is demonstrated. The challenge of balancing reactivity and stability was achieved by employing a small, electron-deficient tetrazine bearing an azido group and an enol ether functionalized cyclooctyne. The chemoselective sequence of strain-promoted azide-alkyne cycloaddition (SPAAC) and inverse-electron-demand Diels-Alder (IEDDA) reaction is demonstrated with