Fig. 3 | Nature Communications

Fig. 3

From: Design and 22-step synthesis of highly potent D-ring modified and linker-equipped analogs of spongistatin 1

Fig. 3

An 18-step synthesis of the fully elaborated ABCD* fragment of the spongistatins. a The synthesis of the redesigned CD* spiroketals 9a and 9b entails as key steps a Mukaiyama aldol reaction and a diastereoselective spiroketalization reaction. b The direct complex fragment coupling syn-crotylation reaction to join AB spiroketal diene 12 with CD* spiroketal aldehyde 9b to produce 25 in a single step is robust and scalable and is the crucial innovation in the development of a highly step-economical and efficient synthesis of the ABCD* fragment of the spongistatins. c Five straightforward steps convert 21 and 25 into the completed ABCD* fragment 6a and linker-equipped analogs 6b and 6c. DBU1,8-diazabicyclo[5.4.0]-undec-7-ene, DMAP4-dimethylaminopyridine, TASF tris(dimethylamino)sulfonium difluorotrimethylsilicate

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