A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
Disclosed is a new, catalytic, and general methodology for the chemical synthesis of biaryl, heterobiaryl, and polyaryl molecules by the cross-coupling of o-methoxybenzamides with aryl boroneopentylates. The reaction is based on the activation of the unreactive C-OMe bond by the proximate amide directing group using catalytic RuH2(CO)(PPh3)3 conditions. A one-step, base-free coupling process is thereby established that has the potential to supersede the useful two-step directed ortho metalation/cross-coupling reaction involving cryogenic temperature and strong base conditions. High regioselectivity, orthogonality with the Suzuki-Miyaura reaction, operational simplicity, minimum waste, and convenient scale-up make these reactions suitable for industrial applications.
A new, catalytic, and general methodology for the synthesis of biaryls and heterobiaryls by the cross coupling of anthranilamide derivatives (o-NMe2 benzamides) with aryl boroneopentylates is described. The reaction proceeds under catalytic RuH2(CO)(PPh3)3 conditions driven by the activation of the unreactive C-N bond by amide directing group (DG)-Ru catalyst chelation. High regioselectivity, orthogonality with the Suzuki-Miyaura reaction, operational simplicity, and convenient scale-up are features of these reactions which may lend themselves to industrial applications.
A new and general synthetic methodology for the construction of biaryl, heterobiaryl, and polyaryl molecules by the ruthenium-catalyzed cross-coupling of ortho-methoxy naphthamides with aryl boroneopentylates is described. The isomeric 1-MeO-2-naphthamides and 2-MeO-1-naphthamides furnish an expansive series of arylated naphthamides in excellent yields. Competition experiments showed the higher reactivity of 1-MeO-2-naphthamide over 2-MeO-benzamide. Orthogonality between the C-O activation/cross-coupling and the Suzuki-Miyaura reactions was established. The method provides naphthalenes which are difficult to prepare by directed ortho metalation.
A general, mild, and efficient method for the reductive cleavage of aryl O-carbamates to phenols, 1 → 2 using the Schwartz reagent is reported. The method is selective, tolerating a large number of functional groups; may be carried out by direct or by an economical in situ procedure; and, notably, establishes a synthetic connection to the directed ortho metalation strategy (Figure 1 ) allowing new entries into difficult to prepare contiguously substituted aromatics and heteroaromatics.
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