scholarly journals Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

2015 ◽  
Vol 11 ◽  
pp. 1649-1655 ◽  
Author(s):  
Hanmo Zhang ◽  
E Ben Hay ◽  
Stephen J Geib ◽  
Dennis P Curran
Keyword(s):  
Carbonyl Group ◽  
Ring Opening ◽  
Radical Cyclizations ◽  
Type Reaction ◽  
Primary Products ◽  
Lactam Carbonyl Group ◽  
Lactam Carbonyl ◽  
Imine Reduction ◽  
Derivatives Of

Two new fates of imine intermediates formed on radical cyclizations of ene-sulfonamides have been identified, reduction and hydration/fragmentation. Tin hydride-mediated cyclizations of 2-halo-N-(3-methyl-N-sulfonylindole)anilines provide spiro[indoline-3,3'-indolones] or spiro-3,3'-biindolines (derived from imine reduction), depending on the indole C2 substituent. Cyclizations of 2-haloanilide derivatives of 3-carboxy-N-sulfonyl-2,3-dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retro-Claisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles.

Sulfur-free Penicillin Derivatives. II. Functionalization of the Methyl Groups

1972 ◽  
Vol 50 (17) ◽  
pp. 2898-2902 ◽  
Author(s):  
Saul Wolfe ◽  
Wha Suk Lee ◽  
Jean-Bernard Ducep ◽  
Gérard Kannengiesser
Keyword(s):  
Carbonyl Group ◽  
Ring Opening ◽  
Methyl Groups ◽  
Cephalosporin C ◽  
Lactam Carbonyl Group ◽  
Molar Equivalent ◽  
Lactam Carbonyl

Allylic bromination of anhydropenicillin chlorination products by N-bromosuccinimide (NBS) is described. With two molar-equivalents of NBS both methyl groups are functionalized; with one molar-equivalent of NBS a mixture of Z and E monobrominated isomers is obtained.Nitrogen and oxygen nucleophiles attack the dibrominated derivatives at the β-lactam carbonyl group, with concomitant ring-opening. However, the mono-brominated derivatives undergo ready displacement by azide and formate ions. The mechanism of these reactions, leading to preferred formation of Z-isomer, is discussed.Cyclization of the allylic formates yields sulfur-free derivatives corresponding to the cephalosporin Cc class of compounds.

scholarly journals Intramolecular Aza-Wittig Reaction of Iminophosphoranes with the b-Lactam Carbonyl Group

1997 ◽  
Author(s):  
Mateo Alajarín ◽  
Pedro Molina ◽  
Angel Vidai ◽  
Fulgencio Tovar
Keyword(s):  
Carbonyl Group ◽  
Wittig Reaction ◽  
Lactam Carbonyl Group ◽  
Lactam Carbonyl

ChemInform Abstract: The First Aza-Wittig Reaction of the β-Lactam Carbonyl Group.

ChemInform ◽  
2010 ◽  
Vol 30 (8) ◽  
pp. no-no
Author(s):  
M. ALAJARIN ◽  
P. MOLINA ◽  
A. VIDAL ◽  
F. TOVAR
Keyword(s):  
Carbonyl Group ◽  
Wittig Reaction ◽  
Lactam Carbonyl Group ◽  
Lactam Carbonyl

Derivatives of isatin in aqueous solution. I. Kinetics of ring opening of Isatin-5-sulfonate

1981 ◽  
Vol 34 (2) ◽  
pp. 365 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Ring Opening ◽  
Rate Of Change ◽  
Spectroscopic Methods ◽  
Ph Values ◽  
Buffer Region ◽  
Pka Value ◽  
Back Titration ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sulfonate Anion

The reactions of isatin-5-sulfonate anion (si-) which cause a hysteresis in pH titrations were studied by pH-metric and n.m.r, spectroscopic methods. Rapid alkalimetric titrations [I 0.15 M (KNO3),37�] gave the pKa value corresponding to the addition of OH- to si- [pKa(ring) 9.55]. The slow ring opening to the sulfonatoisatate dianion (sia2-) led to a drift of the pH values towards an equilibrium buffer region. Its pKa, value [pKa(eq) 3.44] corresponds to the reaction si-+H2O ↔ sia 2-+H+ Rapid back-titration gave the pKa value of the ring-opened species Hsia- [pKa(open) c. 1.3]. The rate law for the ring opening d[sia]/dt=k2 [siOH](OH)+k1*[si] was obtained from the rate of change of pH. N-Methylisatin-5-sulfonate behaves analogously.

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