Generation of Carbamoyl- and Thiocarbamoyllithium Synthons Having a Hydrogen(s) or an Aryl Group on the Nitrogen and Their Trapping with Carbonyl Electrophiles

Abstract

Dimetalated amides 1 (Y = O) were generated as the synthons of carbamoyllithiums 2 (Y = O) by the reaction of isocyanates with iBu2AlTenBu and a subsequent tellurium-lithium exchange reaction. A series of amide derivatives 3 (Y = O) were obtained by the trapping of dianion 1 with electrophiles. This transformation can be successfully applied to the generation and trapping of thiocarbamoyllithium synthons 1 (Y = S) as well as to the nucleophilic introduction of the parent carbamoyl moiety H2NC(O).

Diastereoselective Aza‐Mislow–Evans Rearrangement of N‐Acyl tert‐Butanesulfinamides into α‐Sulfenyloxy Carboxamides

“…I nb oth cases,t he enantiomeric ratio was maintained. [16] Under thio-Arbuzov reaction conditions (BnBr), [17] the expected a-bromo amide product derived from 2c did not form;instead, the S À Obond-cleavage product 5 was obtained in 76 %y ield with an excellent enantiomeric ratio [Eq. We rationalize the observed enantioselectivity as follows: Mislow-Evans rearrangement is commonly thought to involve five-membered cyclic endo transition states.…”

Diastereoselective Aza‐Mislow–Evans Rearrangement of N‐Acyl tert‐Butanesulfinamides into α‐Sulfenyloxy Carboxamides

“…[16] Under thio-Arbuzov reaction conditions (BnBr), [17] the expected a-bromo amide product derived from 2c did not form;instead, the S À Obond-cleavage product 5 was obtained in 76 %y ield with an excellent enantiomeric ratio [Eq. Thec ommon thiophile P(OMe) 3 readily cleaved the S À Ob ond of rearrangement product 2d in methanol at room temperature to yield ahydroxyamide 3 in 90 %y ield, and the Grignard reagent MeMgBr effectively promoted bond cleavage at À78 8 8C [Eq.…”

Generation and Reaction of Carbamoyl Anions in Flow: Applications in the Three‐Component Synthesis of Functionalized α‐Ketoamides

“…[9] Lithium-tellurium exchange, [10] lithium-hydrogen exchange,o rd eprotonation of formamides with lithium diisopropylamide (LDA), [11] and reductive lithiation [12] can also be used for generating carbamoyllithium. [9] Lithium-tellurium exchange, [10] lithium-hydrogen exchange,o rd eprotonation of formamides with lithium diisopropylamide (LDA), [11] and reductive lithiation [12] can also be used for generating carbamoyllithium.…”