α-Fluoroamine synthesis via P(III)-mediated deoxygenative geminal fluorosulfonimidation of 1,2-diketones

Efficient Synthesis of Cyanohydrin Esters: P(NMe2)3 Mediated Direct Deoxygenation of Acyl Cyanides with Carboxylic Acids

An efficient synthesis of cyanohydrin esters via a P(NMe2)3 mediated direct deoxygenation process has been exploited, circumventing the release or transformation of the CN─ anion during the reaction. This approach possesses a broad scope and acts as a powerful supplement for the construction of diverse cyanohydrin esters. It offers advantages such as mild conditions, straightforward operations, and excellent scalability, affirming the feasibility and versatility of this approach and highlighting its potential in practical synthesis.

P(NMe2)3-Mediated Regioselective N-Alkylation of 2-Pyridones via Direct Deoxygenation of α-Keto Esters

A practical and regioselective direct N-alkylation of 2-pyridones is enabled by use of α-keto esters in the P(NMe2)3-mediated deoxygenation process. The reaction proceeds under mild conditions to produce N-alkylated 2-pyridones with high selectivity and generality, and the protocol is shown to be applicable for the scale-up synthesis, which makes it promising for practical applications.

Relayed Heteroatom Group Transfer: A Structural Reorganization between Bisthioester and Triaminophosphine to α,α-Disulfenylamide

Simultaneous multiple displacements of organic molecules can lead to a large structural reconstruction with increased complexity that would be difficult to access otherwise. Whereas double displacement such as olefin metathesis is well-established, higher-order versions remain much more challenging, because of their intrinsic thermodynamic disadvantages. Here, we describe a newly discovered relayed heteroatom group transfer process between bisthioesters and triaminophosphines as an unusual example of a formal triple displacement. Through the oxygen/nitrogen exchange between the two simple starting materials, in addition to the 1,2-sulfur migration of a putative carbene intermediate, an organized relocation of the O/S/N groups proceeded to give a variety of α,α-disulfenylamides with excellent efficiency under ambient conditions. The experimental and computational mechanistic studies revealed the sequence of the relayed group shifts via an α,α-disulfenyl phosphonium enolate intermediate as well as the dual role of triaminophosphine as both an oxygen acceptor and a nitrogen donor.

Access to Multifunctionalized Tetrasubstituted Carbon Centers Bearing up to Three Different Heteroatoms via Tandem Geminal Chlorofluorination of 1,2-Dicarbonyl Compounds

The incorporation of noncarbon heteroatoms into organic molecules typically instills characteristic and often valuable functionalities. The copresence of different heteroatoms can further broaden their utility through the synergistic cooperative effects, which may even lead to the discovery of formerly unavailable properties that are not just a simple accumulation of each function. However, despite increasing interest in the controllable installation of heteroatoms, it has been extremely challenging to construct carbon centers having three different heteroatoms in a synthetically useful manner. In this work, our group's tandem geminal chlorofluorination (Cl, F) strategy was applied to rationally designed heteroatom-bearing 1,2-dicarbonyl substrates, including α-keto thioesters (S), α-keto N-acylindoles (N), and α-keto acylsilane (Si), which resulted in the practical production of doubly or triply heterofunctionalized tetrasubstituted carbon centers with excellent site-selectivity.

Sequential In Situ-Formed Kukhtin-Ramirez Adduct and P(NMe2)3-Catalyzed O-Phosphination of α-Dicarbonyls with P(O)-H

O-Phosphination of α-dicarbonyls via sequential in situ formation of a Kukhtin-Ramirez adduct and a P(NMe2)3-catalyzed process has been exploited for the synthesis of α-phosphoryloxy carbonyls. A range of P(O)-H derivatives, including diarylphosphine oxides, arylphosphinates, and phosphinates, are competent candidates to be introduced into the α-dicarbonyls in this transformation, and various α-phosphoryloxy carbonyls are obtained. This approach possesses advantages of mild conditions, simple operations, atom economy, high efficiency, and gram-scale synthesis, which make it promising in the synthesis toolbox.

Fluorine-Assisted Rearrangement of Geminal Azidofluorides to Imidoyl Fluorides

Organoazide rearrangement constitutes versatile synthetic strategies but typically requires an extremely strong acid and/or a high reaction temperature. Our group recently discovered the remarkable accelerating effect of the geminal fluorine substituent that enables the facile rearrangement of azides into imidoyl fluorides without the aid of acid under much milder reaction conditions. The role of geminal fluorine was elucidated by both experimental and computational investigations. This new reactivity led to the development of a practical one-step tandem preparative method for potentially useful and bench-stable imidoyl fluorides from a wide range of structurally diverse geminal chlorofluorides. Our additional efforts to expand the reaction scope regarding the migrating group, halogen, and carbonyl function are described, and the synthetic utility of the imidoyl fluoride products was demonstrated in hopes of promoting the use of this under-appreciated functional group in the synthetic organic community.