Facile Synthesis of Functionally Substituted Cyclopentenones and Butenolides from Functional Vinyl Carbanions

Abstract

CAS Registry numbers: (I), 6130-87-6; (Za), 6669-81-4; ( 2 b ) , 65651-89-0; ( 2 c ) , 65651-91-4; ( 2 d ) , 65651-92-5; ( 4 a ) , 65651-93-6; ( 4 b ) , 25286-68-4; ( 4 c ) , 65651-94-7; ( 4 d ) , 65651-95-8; ( 4 e ) , 65651-83-4; (I), R=CHs, Z=CN, 65651-84-5; (5), 65651-86-7; iodomethane, 74-88-4; methylium tetraphenylborate, 65701-71 -5; ethylium tetrafluoroborate, 65651-87-8; methyl trifluoromethanesulfonate, 333-27-7 Model Compounds for the Study of N2 Eliminations under the Influence of Electrophiles, Part 12. 3. Org. Chem. 35,960 (1970): cf. formation of 3,3-dialkyl-l-tosyltriazenes from 1,l-dialkylhydrazine anions and tosyl azide. E. uon Meyer, J. Prakt. Chem. 63, 173 (1901). The compounds prepared were characterized by analysis and spectroscopy.

The Alkylation of Carbanions

“…Acrylic acid derivatives with a heteroatom (N, O, S, Hal) at C-3 can be cleanly deprotonated at this position with BuLi or LDA at low temperatures [329,[333][334][335][336][337][338] (Scheme 5.37). Some of these anions rearrange to the a-metalated acrylates on warming [329], but can also decompose (see Section 5.4.7).…”

Acylvinyl and Vinylogous Synthons

“…Similarly, β-lithiated β-amino-substituted acrylate derivatives type 181 (X = R 2 N; Z = CO 2 Me or CO 2 Et) have also been employed for the synthesis of tetronates, butenolides, and cyclopentenones, as well as β-lithiated β-amino- 95,96 or thio-substituted 97 acrylamides. Even ( E )-cinnamic esters ( 181 , X = Ph; Z = CO 2 Et) can be metalated at the β-position with lithium diisopropylamide and react stereoselectively with electrophiles .…”

“…91 However, the use of systems such as racemic 185 for the preparation of cyclopentenones 186 afforded rather low stereocontrol (2:1 diastereomer ratio) (Scheme 41). 92 Similarly, β-lithiated β-amino-substituted acrylate derivatives type 181 (X ) R 2 N; Z ) CO 2 Me or CO 2 -Et) have also been employed for the synthesis of tetronates, 93 butenolides, 94 and cyclopentenones, 94 as well as β-lithiated β-amino- 95,96 or thio-substituted 97 acrylamides. Even (E)-cinnamic esters (181, X ) Ph; Z ) CO 2 Et) can be metalated at the β-position with (E)-N-Isopropyl-3-(p-toluenesulfonyl)acrylamide ( 128), prepared as mentioned previously from Nisopropylacrylamide by a tandem iodosulfonylationdehydroiodination reaction, 99 could give a reagent type 181 (X ) p-TolSO 2 ; Z ) CONLiR) which uses the stabilizing and directing effect of the sulfonyl group in metalation reactions.…”

1-Alkenyllithium-Reagentien mit einem Heteroatomsubstituenten in derα-Position: Carbanionen und Carbenoide zur C-C-Verknüpfung

“…Beispiele für solche deprotonierbaren Enamine sind Derivate von b-Aminoacrylsäuren (Amid, Ester und Nitril), deren Lithiumderivate 28, R 2 (CH 2 ) 4 , (CH 2 ) 3 , allerdings auûerordentlich labil sind und bei À 120 8C erzeugt und umgesetzt werden müssen. [64] ¾hnlich instabil sind lithiierte Isocyanide 29, [65] während metallierte Amidine 30 [Gl. (9)] bei À 78, einige sogar bei À 20 8C in Lösung haltbar sind.…”