Dual nickel/photocatalytic C–N couplings are performed with an organic heterogeneous photocatalyst, in an oscillatory plug flow reactor. Reaction was complete in 20 min residence time, enabling 2.7 g h−1 throughput and 10-fold catalyst recycling.

SummaryPhosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond.

Continuous flow reactor technology has a proven track record in enabling photochemical transformations. However, transfer of a photochemical batch process to a flow protocol often remains elusive, especially when solid reagents or catalysts are employed. In this work, application of an oscillatory plug flow photoreactor enabled a heterogeneous MacMillan-type C(sp²) -C(sp³) cross-electrophile coupling. Combination of an oscillatory flow regime with static mixing elements imparts exquisite control over mixing intensity and residence time distribution (RTD), pinpointing a mindset shift concerning slurry handling in continuous flow reactors. The C(sp²) -C(sp³) cross-electrophile coupling was successfully transferred from batch to flow, resulting in an intensified slurry process with significantly reduced reaction time and increased productivity (0.87 g/h).

Diphosphonylated diazaheterocyclic compounds were synthesized in a one‐step reaction by using dimethyl trimethylsilyl phosphite (DMPTMS) under acidic conditions. The reaction of DMPTMS with 1,5‐naphthyridine yielded the corresponding diphosphonylated product through a tandem 1,4–1,2 addition under microwave conditions. This tandem 1,4–1,2 addition was also evaluated for other substrates, namely, 1,10‐phenanthroline, 1,7‐phenanthroline and 4,7‐phenanthroline. Reactions under reflux and microwave conditions were compared. 1,5‐Naphthyridine and the phenanthroline derived substrates are less reactive than previously investigated quinolines. The experimental trends in reactivity were rationalized by means of theoretical calculations. The intrinsic properties, such as aromaticity and proton affinities, showed distinct differences for the various substrates. Furthermore, the calculated free energies of activation for the rate‐determining step of the tandem addition reaction enabled us to rationalize the differences in product yields. Both the theoretical and the experimental results show the substantial influence of the position of the nitrogen atoms in the (poly)aromatic compounds on the reaction outcome.

This review covers the formation of N-a nd S-containing heterocycles,i nitiated by gold-catalyzed nucleophilic attack of N-o rS-nucleophiles ontoa lkynes. These typeso fn ucleophiles have been somewhat overlooked as compared to their C-o rO-counterparts in other reviews.I nt his particularw ork, their intramolecular gold-mediated attack ontoa lkynesi sr eviewedi nd epth.I ti ss tructured in such af ashion that the reader will get ac learv iew of which substrates react in which cyclization mode. 1I ntroduction 2N-Nucleophiles 2.Scheme1.endo-a nd exo-dig cyclization modes for heteroatom attack onto Au-activated triple bonds. REVIEWSWouter Debrouwer et al. Scheme 2. Au(I)-catalyzed formationo fp yrroles from homopropargylic azidesb yana cetylenic Schmidt reaction. Scheme3.AuCl 3 -catalyzed preparation of fluorinated pyrroles.Scheme4.Pyrrole synthesis according to Aponick and Akai. REVIEWSHomogeneous Gold-Catalyzed Cyclization Reactions of Alkynes Scheme 32. Formationo fp yrroles via 5-exo-dig cyclization with acationic Au(I) catalyst.Scheme 33. Formationo fhomoallylic pyrroles via aza-Claisen rearrangement according to Gagosz. REVIEWSHomogeneous Gold-Catalyzed Cyclization Reactions of Alkynes Scheme 58. Au-catalyzed hydroamination in the total synthesis of (À)-Quinocarcin.Scheme 59. Reactionb etween o-alkynylbenzaldehydes and anilines under AuCl catalysis.Scheme60. Intramolecular hydroamination and transfer hydrogenation. REVIEWSHomogeneous Gold-Catalyzed Cyclization Reactions of Alkynes Scheme 79. Generation of ac ontact ion pair with retention of stereochemistry,a nd the unobserved sigmatropicr earrangement with inversion of stereochemistry.Scheme 80. Au(III)-catalyzed cycloisomerization with formation of dihydrothiazoles.Scheme81. Au(I)-catalyzed generation of an Au-carbene.

A three-step synthesis of benzo[c]thiophenes is presented in which the key transformation is the gold-catalyzed 5-exo-dig migratory cycloisomerization of a diallyl thioacetal. It was shown that a small amount of in situ generated HAuCl4 from AuCl3 is the active catalytic species. A mechanism was proposed.

3-Azabicyclo[3.1.0]hex-2-en-1-yl phosphonates were prepared in a five-step reaction route from β-ketophosphonates. The key steps in this sequence are an atom-transfer radical cyclization and an unforeseen lithium-halogen exchange with n-BuLi. The cyclization reaction proceeds with excellent diastereoselectivity. The resulting cyclic imines were reduced, and 3-azabicyclo[3.1.0]hexan-1-yl phosphonates were obtained.

Phosphonylated pyrroles were obtained by a ZnCl2-catalyzed 5-exo-dig hydroamination of propargylic enamines. These starting compounds were obtained in two steps from commercially available β-ketophosphonates. The method tolerates a wide variety of substituents at the 1,2- and 5-position of the pyrrole, while further derivatization allows for the introduction of substituents at the 4-position via lithiation or halogenation.