Science and Nature

Photomediated ring contraction of saturated heterocycles

Shuffling nitrogen with a gentle push

Manipulation of carbon–nitrogen rings is integral to the synthesis of diverse pharmaceutical and agrochemical compounds. Jurczyk et al. file that photoexcitation of carbonyl-substituted cyclic amines can shift the nitrogen from internal to initiating air the ring framework. The response appears to be like to be to proceed thru a 1,5-hydrogen shift to the electronically angry carbonyl, which sets in motion the next carbon–nitrogen and carbon–carbon bonding rearrangements. Loads of oxygen and sulfur heterocycles had been appropriate as nicely. Addition of a chiral phosphoric acid catalyst rendered the response uneven.

Science, abi7183, this explain of affairs p. 1004


Saturated heterocycles are present in a gargantuan option of therapeutics and bioactive pure products and are noteworthy in many medicinal and agrochemical compound libraries. To compile admission to unique chemical home and earn, many programs for functionalization on the periphery of these structures had been developed. Comparatively fewer programs are known for restructuring their core framework. Herein, we characterize a visible gentle–mediated ring contraction of α-acylated saturated heterocycles. This unconventional transformation is orthogonal to mature ring contractions, disturbing the paradigm for diversification of heterocycles at the side of piperidine, morpholine, thiane, tetrahydropyran, and tetrahydroisoquinoline derivatives. The success of this Norrish kind II variant rests on reactivity differences between photoreactive ketone groups in converse chemical environments. This intention used to be utilized to slack-stage transforming of pharmaceutical derivatives, peptides, and sugars.

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