Kumulierte Ylide, VII. Eine Methode zum Aufbau α,β‐ungesättigter Carbonsäurederivate

Abstract

Phosphacurnulen-Ylide 1 addieren Alkohole, Thiole und NH-acide Verbindungen zu Phosphoranen 3, die sich mit Aldehyden LU Estern, Thioiestern, Imidsaureestern, Imidsaurethioestern, Amidinen, Azoiiden sowie Suifonamiden a,D-ungesattigter Carbonsauren umsetzen lassen.Cumulated Ylides, VII') A Method for the Synthesis of r&Unsaturated Carboxylic Compounds Phosphacumulene ylides 1 add alcohols, thiols, and NH-acidic compounds to form phosphoranes 3, which react with aldehydes t o give esters, thiol esters, imidates, thioimidates, amidines, azolides, and sulfonamides of a$-unsaturated carboxylic acids.

Telescoping Reactions with Trifluorodiazoethane‐Derived Aza‐Wittig Reagents and Allenyl esters

“…[23][24][25][26][27] First, we utilized phosphorane 3a,w hich featured the triphenylphosphine group, but no reaction occurred. [23][24][25][26][27] First, we utilized phosphorane 3a,w hich featured the triphenylphosphine group, but no reaction occurred.…”

“…Next, a-iminophosphoranes 3 were anticipated to react with aldehydes in aW ittig reaction, similar to work reported by the group of Wittig and others. [23][24][25][26][27] First, we utilized phosphorane 3a,w hich featured the triphenylphosphine group, but no reaction occurred. Next, we attempted thes ame reaction with tributylphosphorane 3g.S urprisingly,t he Wittig product was not detected;i nstead, b-enamino ester 4a was obtained in good yield with complete Z-stereoselectivity (Scheme 6a).…”

“…Next, α‐iminophosphoranes 3 were anticipated to react with aldehydes in a Wittig reaction, similar to work reported by the group of Wittig and others . First, we utilized phosphorane 3 a , which featured the triphenylphosphine group, but no reaction occurred.…”

Synthesis and Cyclization Reactions of Axially Chiral N‐Sulfamoyl‐acrylamidines

“…However, the use of the corresponding amidines is much less documented , though the amidine group deserves special interest as a pharmacophore and as a constituent of natural products . Actually, there is only a limited array of synthetic methods for α,β‐unsaturated amidines: besides nitrile‐based‐methods , there are olefination methods and the option of desulfurization of an isothiazol‐5(2 H )‐imine . Another special feature of amidine chemistry is N ‐sulfonyl substitution giving a structural motif of natural products and of bioactive compounds .…”

Preparation of N-(α,β-unsaturated acyl)-sulfonamides

“…Published preparations of N-(α,β-unsaturated acyl)sulfonamides include (i) the acylation of sulfonamides (RSO 2 NH 2 ) by (a) unsaturated acyl chlorides (R'CH=CHCOCl) in the presence of a base (such as triethylamine, 3,5a n-butyllithium, 4d or NaH 6,7 ) or a copper powder catalyst; 8 (b) unsaturated carboxylic acids via mixed anhydride in the presence of Lewis acid catalyst; 9 (ii) reactions of aryl isocyanates (RSO 2 NCO) with 1-alkenyltrialkylstannanes, di-1-alkenyldibutylstannanes in the presence of aluminium trichloride 10a or with substituted alkenes; 10b (iii) reactions of sulfonamide with the Wittig adduct obtained from (triphenylphosphoranylidene)ketene and an aldehyde; 11 (iv) coupling of unsaturated acids with sulfonamides in the presence of 1-ethyl-3-(3'-dimethylaminopropyl)carbodiimide (EDCI); 2,3,12 (v) dehydrogenation of the corresponding saturated analogs by using LDA followed by N-tertbutylbenzenesulfinimidoyl chloride. 5a,13 Herein, we report the acylation of sulfonamides with stable, crystalline N-(α,β-unsaturated acyl)benzotriazoles to give N-(α,β-unsaturated acyl)sulfonamides.…”