Catalytic approaches to assemble cyclobutane motifs in natural product synthesis

Abstract

New strategies based on transition-metal catalysis or organocatalysis have provided new perspectives into the total synthesis of cyclobutane-containing natural products.

High‐Throughput Ligand Screening Enables the Enantioselective Conjugate Borylation of Cyclobutenones to Access Synthetically Versatile Tertiary Cyclobutylboronates

“…[2] Compared to cyclopentane and cyclohexane homologues, far fewer synthetic methods exist to produce functionalized chiral cyclobutanes in high enantioselectivity. [3] Owing to the versatility of the boronyl substituent as ap recursor to CÀO, C À N, C À C, and C À Xbonds,there is significant interest in the development of efficient methods to prepare chiral cyclobutylboronates in optically enriched form. Moreover,t he boronyl unit can be employed as apotential handle to install ac yclobutyl unit into am edicinal scaffold via transition-metal-catalyzed Suzuki-Miyaura cross-coupling or O-/Narylation.…”

High‐Throughput Ligand Screening Enables the Enantioselective Conjugate Borylation of Cyclobutenones to Access Synthetically Versatile Tertiary Cyclobutylboronates

“…Compared to cyclopentane and cyclohexane homologues, far fewer synthetic methods exist to produce functionalized chiral cyclobutanes in high enantioselectivity . Owing to the versatility of the boronyl substituent as a precursor to C−O, C−N, C−C, and C−X bonds, there is significant interest in the development of efficient methods to prepare chiral cyclobutylboronates in optically enriched form.…”

Synthesis of sinapine and its unprecedented ruthenium-catalyzed [2+2] photodimerization

“…Although these strained mono-cyclic rings were regarded in the beginning to be somewhat exotic; they could be found and isolated in many plants but only in a very tiny amount, but curiosity in these molecules together with the better isolation techniques and the development of synthetic strategies enable access to many of them. This development was driven in particular by the fact that some cyclobutanoid dimers [5][6][7][8][9][10] , such as innovanoside A, showed high biological activity. Furthermore, numerous cyclobutanoids of superior biological activity were isolated from the Piper genus, such as dipiperamides A-E [11][12][13][14][15][16][17][18] and piperarborenines A-E [19][20][21][22][23][24][25][26][27][28] (Scheme 1) and several total syntheses have been developed.…”