A Stereoselective Synthesis of Alkynylaziridines

Abstract

Reactions between allenylzinc carbenoid 1 and various imines were examined; trans-substituted alkynylaziridines were produced with excellent diastereoselectivity.

Synthesis of Substituted 1,4,5,6-Tetrahydrocyclopenta[ b ]pyrroles by Platinum-Catalyzed Cascade Cyclization/Ring Expansion of 2-Alkynyl-1-azaspiro[2.3]hexanes

“…The substrates 1 for the cyclization reactions were synthesized as follows (Scheme ). After the reaction of cyclobutanone ( 3a ) with benzylamine, the resulting imine was treated with the allenylzinc reagent to give the TMS-substituted propargylic aziridine 4a . Compound 4a was subjected to the reaction with K 2 CO 3 in MeOH to afford the desilylated compound 5a , and then various substituents at the terminal position of the alkyne 5a were introduced to give 1a – e by the reactions with BuLi and the corresponding alkyl bromides.…”

Synthesis of Substituted 1,4,5,6-Tetrahydrocyclopenta[ b ]pyrroles by Platinum-Catalyzed Cascade Cyclization/Ring Expansion of 2-Alkynyl-1-azaspiro[2.3]hexanes

“…The substrates 1 for the cyclization reactions were synthesized as follows (Scheme ). After the reaction of cyclobutanone ( 3a ) with benzylamine, the resulting imine was treated with the allenylzinc reagent to give the TMS-substituted propargylic aziridine 4a . Compound 4a was subjected to the reaction with K 2 CO 3 in MeOH to afford the desilylated compound 5a , and then various substituents at the terminal position of the alkyne 5a were introduced to give 1a – e by the reactions with BuLi and the corresponding alkyl bromides.…”

1,2-Additions on Chiral N-Sulfinylketimines: An Easy Access to Chiral α-Tertiary Amines

“…In 2004, Ferreira and co-workers performed the addition of a racemic 3-chloroallenylzinc to N -sulfinylaldimines and -ketimines leading to enantioenriched aziridines by kinetic resolution of the chiral organometallic (Scheme 24 , top). 33a b They also reported an example of the addition of racemic protected 3-hydroxyallenylzinc leading to an acetylenic 1,2-amino alcohol (Scheme 24 , bottom). 33c…”

Highly Diastereoselective Syntheses of Propargylic Acid and Homopropargylic Systems

“…The same reaction was then tested with Ntrimethylsilylimines 59,60 (Table 9), which were found to be more reactive than the N-benzyl ones as the reaction with 13 occurs below -35°C. Unlike N-benzylaziridines 21, the stereochemistry of the N-H aziridines 22 obtained after hydrolysis cannot be assigned by 1 H NMR since broad signals are observed for their aziridinyl protons.…”

Synthesis of Substituted 1,4,5,6-Tetrahydrocyclopenta[ b ]pyrroles by Platinum-Catalyzed Cascade Cyclization/Ring Expansion of 2-Alkynyl-1-azaspiro[2.3]hexanes

“…The substrates 1 for the cyclization reactions were synthesized as follows (Scheme ). After the reaction of cyclobutanone ( 3a ) with benzylamine, the resulting imine was treated with the allenylzinc reagent to give the TMS-substituted propargylic aziridine 4a . Compound 4a was subjected to the reaction with K 2 CO 3 in MeOH to afford the desilylated compound 5a , and then various substituents at the terminal position of the alkyne 5a were introduced to give 1a – e by the reactions with BuLi and the corresponding alkyl bromides.…”

1,2-Additions on Chiral N-Sulfinylketimines: An Easy Access to Chiral α-Tertiary Amines

“…In 2004, Ferreira and co-workers performed the addition of a racemic 3-chloroallenylzinc to N -sulfinylaldimines and -ketimines leading to enantioenriched aziridines by kinetic resolution of the chiral organometallic (Scheme 24 , top). 33a b They also reported an example of the addition of racemic protected 3-hydroxyallenylzinc leading to an acetylenic 1,2-amino alcohol (Scheme 24 , bottom). 33c…”

Highly Diastereoselective Syntheses of Propargylic Acid and Homopropargylic Systems

“…The same reaction was then tested with Ntrimethylsilylimines 59,60 (Table 9), which were found to be more reactive than the N-benzyl ones as the reaction with 13 occurs below -35°C. Unlike N-benzylaziridines 21, the stereochemistry of the N-H aziridines 22 obtained after hydrolysis cannot be assigned by 1 H NMR since broad signals are observed for their aziridinyl protons.…”

Synthesis of Substituted 1,4,5,6-Tetrahydrocyclopenta[ b ]pyrroles by Platinum-Catalyzed Cascade Cyclization/Ring Expansion of 2-Alkynyl-1-azaspiro[2.3]hexanes

“…The substrates 1 for the cyclization reactions were synthesized as follows (Scheme ). After the reaction of cyclobutanone ( 3a ) with benzylamine, the resulting imine was treated with the allenylzinc reagent to give the TMS-substituted propargylic aziridine 4a . Compound 4a was subjected to the reaction with K 2 CO 3 in MeOH to afford the desilylated compound 5a , and then various substituents at the terminal position of the alkyne 5a were introduced to give 1a – e by the reactions with BuLi and the corresponding alkyl bromides.…”

1,2-Additions on Chiral N-Sulfinylketimines: An Easy Access to Chiral α-Tertiary Amines

“…In 2004, Ferreira and co-workers performed the addition of a racemic 3-chloroallenylzinc to N -sulfinylaldimines and -ketimines leading to enantioenriched aziridines by kinetic resolution of the chiral organometallic (Scheme 24 , top). 33a b They also reported an example of the addition of racemic protected 3-hydroxyallenylzinc leading to an acetylenic 1,2-amino alcohol (Scheme 24 , bottom). 33c…”

Highly Diastereoselective Syntheses of Propargylic Acid and Homopropargylic Systems

“…The same reaction was then tested with Ntrimethylsilylimines 59,60 (Table 9), which were found to be more reactive than the N-benzyl ones as the reaction with 13 occurs below -35°C. Unlike N-benzylaziridines 21, the stereochemistry of the N-H aziridines 22 obtained after hydrolysis cannot be assigned by 1 H NMR since broad signals are observed for their aziridinyl protons.…”