No abstract

A highly selective Mn(I)-catalyzed alkenylation of arenes and heteroarenes with 1,3-diynes is described. The reported transformation overcomes regio-, chemo-, and stereoselectivity challenges associated with the use of these coupling partners. Both symmetrical and unsymmetrical diynes can be applied in this protocol, affording single isomers not only in the synthesis of 1,3-enynes but also in the one-step preparation of pyrroles and furans. This simple strategy features wide functional group tolerance, good reproducibility, and preparative scale utility. The manganese catalyst plays a crucial role in this C−H activation protocol, enabling high selectivity with previously challenging internal alkynes. Furthermore, the synthetic value of the method is highlighted by diverse postsynthesis functionalizations of the final products.

Ap rotocol for the three-component 1,4-carboamination of dienes is described. Synthetically versatile Weinreb amides were coupled with 1,3-dienes and readily available dioxazolones as the nitrogen source using [Cp*RhCl 2 ] 2-catalyzedC À Ha ctivation to deliver the 1,4-carboaminated products.T his transformation proceeds under mild reaction conditions and affords the products with high levels of regioand E-selectivity.M echanistic investigations suggest an intermediate Rh III-allyl species is trapped by an electrophilic amidation reagent in ar edox-neutral fashion. Nitrogen-containing molecules are of fundamental importance to pharmaceutical science and can be found in av ast number of bioactive natural products. [1] Difunctionalizations,

Herein, we describe the formation of quaternary carbon centers with excellent diastereoselectivity via a strain-release protocol. An organometallic species is generated by Cp*Rh­(III)-catalyzed C–H activation, which is then coupled with strained bicyclobutanes (BCBs) and a prochiral carbon electrophile in a three-component reaction. This work illustrates a rare example of BCBs in transition metal catalysis and demonstrates their broad potential to access novel reaction pathways. The method developed exhibits ample functional group tolerance, and the products can be further transformed into valuable α-quaternary β-lactones. Preliminary mechanistic investigations suggest a twofold C–C bond cleavage sequence involving σ-bond insertion and an ensuing β-carbon elimination event.

A general and simple strategy for the site-selective thiolation of various pharmaceutically relevant electron-rich heteroarenes with thiols is reported. This mild and reliable photocatalytic protocol enables C–S coupling at the most electron-rich position of the (multi)­halogenated substrates, complementing established methodologies. Experimental and computational studies suggest a radical chain mechanism with the key step being a homolytic aromatic substitution of the heteroaryl halide by an electrophilic thiyl radical, highlighting an underdeveloped reactivity mode.

A practical one-pot C−H formylation approach enabled by the relay catalysis of manganese(I) and iron(III) has been developed. The effect of the directing group exhibited that 2-pyrimidinyl was a suitable directing group to promote the C− H hydroxymethylation and was also compatible in the subsequent aerobic oxidation. This formylation reaction, in which water is the only byproduct, showed high selectivity and efficiency across a broad substrate scope. The use of non-noble transition metals to promote relay catalysis provides a practical and scalable approach to C−H formylation. The loading of the manganese(I) catalyst could be decreased to as low as 0.5 mol % on a 5 g scale reaction.

Herein, we present a mild Cp*Rh III -catalyzed Suzuki−Miyaura-type allyl−aryl coupling of readily accessible arylboron reagents with a broad range of olefins. Allylic arylation was achieved without the need for prefunctionalized alkenes, and the general Heck-type reactivity between olefins and arenes was not observed. Mechanistic studies indicate that the reaction was enabled through the fast generation of a Rh III −allyl species via undirected C(sp 3 )−H activation. Moreover, the developed protocol was applied to the highly concise synthesis of the anti-inflammatory drug flurbiprofen.

We present a concise asymmetric total synthesis (5–8 steps) of nine sesquiterpenoid alkaloids featuring four different tetra‐/pentacyclic scaffolds. To this end, a novel, bioinspired indole N‐terminated cationic tricyclization has been developed, enabling the divergent synthesis of greenwayodendrines and polysin. Subtle variation of the C2‐substituted indole cyclization precursor allowed switching between indole N‐ and C‐termination. For the latter, a subsequent Witkop oxidation enabled conversion of the cyclopentene‐fused indole into the eight‐membered benzolactam to directly furnish the family of greenwaylactams. In addition, a diastereomeric C‐termination product has been elaborated to provide access to polyveoline.