Tf2O/TTBP (2,4,6-Tri-tert-butylpyrimidine): An Alternative Amide Activation System for the Direct Transformations of Both Tertiary and Secondary Amides

POCl3/Sulfoxide-Promoted Synthesis of Indolizino[8,7-b]indoles

A mild chlorocyclization of pyrrole-tethered indoles has been realized using POCl3 as the chlorine source and tetramethylene sulfoxide as the promoter. A variety of chlorinated indolizino[8,7-b]indole derivatives have been constructed efficiently under this reaction system in moderate to good yields (19 examples, up to 93% yield).

Electrochemical synthesis of vicinal azidoacetamides

Vicinal diamines are an important structural motif in bioactive natural products and pharmaceutical intermediates. Herein, an environmentally friendly and efficient electrochemical approach to azidoacetamides, as one variant of vicinal diamines, has been developed. This reaction features mild conditions and broad substrate scope, without the use of any chemical oxidant or transition-metal catalysts. The obtained vicinal azidoacetamides could be conveniently converted into various other vicinal diamine derivatives.

Synthesis of Unsymmetrical Ketones Using Chelation-Controlled Sequential Substitution of N-Triazinylamide/Weinreb Amide by Organometallic Reagents

N-(2,4-Dimethoxy-1,3,5-triazinyl)amide was found to exhibit similar behavior to N-methoxy-N-methylamide (Weinreb amide) but higher reactivity for nucleophilic substitution by organometallic reagents. Triazinylamide suppresses overaddition, leading to the formation of a tertiary alcohol by the chelating ability of the triazinyl and carbonyl groups. Ureas possessing both triazinylamino and methoxy(methyl)amino groups underwent sequential nucleophilic substitution with different organometallic reagents, which furnished unsymmetrical ketones without any detectable tertiary alcohols.

Ir-Catalyzed Chemoselective Reductive Condensation Reactions of Tertiary Amides with Active Methylene Compounds

The catalytic reductive condensation reactions of tertiary amides with active methylene compounds leading to multifunctionalized non-N-containing products is described. The reactions proceed through sequential iridium-catalyzed hydrosilylation of the amides followed by acid-mediated condensation with the active methylene compounds. This scalable method is broad in scope and shows remarkable chemoselectivity for the amide group in the presence of several sensitive or even more reactive functionalities such as ester, cyano, nitro, silyl dienol ether, and ketone.

One-Pot Synthesis of α-Amino Bisphosphonates from Nitriles via Tf2O/HC(OR)3-Mediated Interrupted Ritter-Type Reaction

A versatile synthesis of α-amino bisphosphonates has been achieved through one-pot interrupted Ritter-type reaction under mild conditions. The reactive Ritter intermediate nitrilium is in situ generated by treatment of nitrile with readily accessible Tf₂O/HC(OR¹)₃, which is trapped by phosphite ester to deliver the desired product. This protocol is efficient, scalable, and well compatible with a broad scope of substrates. In addition, plentiful characteristic J_P-C couplings including unusual five-bond long-range ⁵J_P-C and ³J_P-C across quaternary carbon and hetero (N) atoms were observed in ¹³C NMR spectra.

Total synthesis of (±)-vinoxine: construction of the bridged pyrido[1,2-a]indole skeleton via Tf2O-mediated Bischler-Napieralski reaction and stereoselective radical cyclization

The total synthesis of (±)-vinoxine was achieved featuring the assembly of a multi-substituted tetrahydropyrido[1,2-a]indole skeleton through the Tf₂O-mediated Bischler-Napieralski reaction. The characteristic diazabicyclo[3.3.1]nonane skeleton was stereoselectively constructed via radical cyclization based on the one stereochemistry of the C3 position. The established methodology provides new options for the synthesis of natural products and pharmaceuticals containing the multi-substituted pyrido[1,2-a]indole skeleton.

Enantioselective total syntheses of marine natural products (+)-cylindricines C, D, E and their diastereomers

On the basis of the amide strategy, we have achieved the concise enantioselective total synthesis of (+)-cylindricines D, C, and E, and their 2-epimers in seven, eight, and nine steps, respectively.

Tandem Catalysis Enabled Highly Chemoselective Deoxygenative Alkynylation and Alkylation of Tertiary Amides: A Versatile Entry to Functionalized α-Substituted Amines

We report here the highly chemoseive catalytic reductive alkynylation and reductive alkylation of tertiary amides to give propargylamines and α-branched amines, respectively. The method features a tandem iridium (Vaska’s complex)-catalyzed...