Methoxy-Directed Aryl-to-Aryl 1,3-Rhodium Migration

Abstract

Through-space metal/hydrogen shift is an important strategy for transition metal-catalyzed C-H bond activation. Here we describe the synthesis and characterization of a Rh(I) 2,6-dimethoxybenzoate complex that underwent stoichiometric rearrangement via a highly unusual 1,3- rhodium migration. This aryl-to-aryl 1,3-Rh/H shift was also demonstrated in a Rh(I)-catalyzed decarboxylative conjugate addition to form a C-C bond at a meta position instead of the ipso-carboxyl position. A deuterium-labeling study under the conditions of Rh(I)-catalyzed protodecarboxylation revealed the involvement of an ortho-methoxy group in a multi-step pathway of consecutive sp3 and sp2 C-H bond activations.

Metal-Free Protodeboronation of Electron-Rich Arene Boronic Acids and Its Application to ortho-Functionalization of Electron-Rich Arenes Using a Boronic Acid as a Blocking Group

“…Compound 2g was obtained as a white solid. The spectroscopic data of 2g obtained were in good agreement with the literature 30. Yield: 0.064 g (93%, Method B).…”

Arylative Intramolecular Allylation of Ketones with 1,3‐Enynes Enabled by Catalytic Alkenyl‐to‐Allyl 1,4‐Rhodium(I) Migration

“…This intermediate could then undergo a 1,4‐rhodium(I) shift to the cis ‐allylic substituent to give the allylrhodium(I) species B , which could be trapped by an electrophile. This approach was expected to be challenging, given that there is only very limited precedent for rhodium(I) to migrate to C(sp 3 ) centers ,. Nevertheless, the generation of electrophilic allylrhodium(III) species by a similar strategy in our rhodium(III)‐catalyzed oxidative annulations of 1,3‐enynes provided some encouragement .…”

Development of new carbon-carbon bond forming reactions through 1,4-migration of rhodium

“…Carbostannylation of alkynes with allyl-and alkynylstannanes has been achieved using transition metals such as Pd and Ni. 10,11 However, the addition of arylstannanes has not been reported, to the best of our knowledge (Scheme 3.3b). In addition, the rhodium-catalyzed carbometalation of unfunctionalized alkynes has also not been reported.…”

“…Since then, the use of chiral diene ligands has been dramatically developed for rhodium-catalyzed asymmetric 1,4-addition during the past 16 years. 10 A variety of bicyclic diene scaffolds have been successfully employed as ligands to generate the target arylation product in high yield and enantioselectivity. They are bicyclo[2,2,1]heptadiene variations (L8a, L8b, and L8c), 8 bicyclo[2,2,2]octadiene variations (L9a, L9b, L9c, and L9d), 11a-11d bicyclo [3,3,1]nonadiene variations (L10a and L10b), 12 and bicyclo [3,3,2]decadiene variation L11.…”

“…The synthetic utility of arylstannanes has been well established. According to the reported procedures, [23][24][25] tributylstannyl group in 3aa was converted into deuterio (8), iodo (9), and fluoro (10) successfully (Scheme 3.6). The palladiumcatalyzed cross-coupling with an aryl iodide 2 and the rhodium-catalyzed conjugate addition to 2-cyclohexenone 19 gave high yields of the corresponding products, 11…”