97462-73-2

Upstream product

• 50487-70-2 N-allylbenzenesulfonamide 
• 25630-24-4 N,N-diallylbenzenesulfonamide 
• 98-10-2 benzenesulfonamide 
• 97462-71-0 N-(2-bromo-2-propenyl)-N-(2-propenyl)benzenesulfonamide 

Relevant academic research and scientific papers

Triarylphosphine ligands with hemilabile alkoxy groups: Ligands for nickel(II)-catalyzed olefin dimerization reactions. hydrovinylation of vinylarenes, 1,3-dienes, and cycloisomerization of 1,6-dienes

Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl- and 2-benzyloxymethylphenyldiphenylphosphine (L5 and L6, respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at -55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, affording up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II) complexes of 2- benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl- (L6) and 2-benzyloxyethyldiphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II) complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II) complexes of N-heterocyclic carbene ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions.

Diverging effects of steric congestion on the reaction of tributylstannyl radicals with areneselenols and aryl bromides and their mechanistic implications

The effects of bulky ortho,ortho' groups on the reactions of aryl bromides and areneselenols with tributylstannane have been studied. Bulky ortho,ortho' groups accelerate the reaction of the bromides with the stannane but retard the reactions of the selenols. On the other hand, ab initio and force field calculations show that introducing bulky ortho substituents into selenols causes a greater increase in strain than in the corresponding bromides. Two possible explanations for the divergent reactivity patterns are advanced. On one hand, it is possible that bromine abstraction by stannyl radicals from aryl bromides proceeds in a single step through a linear transition state whereas the abstraction of sell from the selenols involves a T-shaped, hypervalent intermediate. Alternatively, it may be that both reactions are concerted with the bromine abstraction having a late transition state and the sell abstraction an early one. Approximate second-order rate constants for the reaction of tributylstannane with a range of hindered aryl bromides are derived from competition reactions. 2,4,6-Tri-tert- butylbenzeneselenol is able to function moderately well as a catalyst for the stannane-mediated reactions of vinyl bromides. The X-ray crystal structure of bis(2,4,6-triisopropylphenyl) diselenide is presented.

Optimizing the 5-exo/6-endo ratio of vinyl radical cyclizations through catalysis with diphenyl diselenide

The 5-exo/6-endo product ratio in the stannane mediated cyclizations of vinyl iodides is very significantly improved by operating in the presence of catalytic PhSeSePh with no loss in overall cyclization yield.

Synthesis of the Pyrrolidine Ring System by Radical Cyclization

A series of bromo-substituted allyl- and diallyl-substituted sulfonamides have been found to undergo free radical cyclization when treated with tri-n-butyltin hydride in the presence of AIBN.The regiochemical course of the cyclization depends on the nature of the substituent groups attached to the ?-bond.The stereoelectronic factors governing the cyclization reaction of these N-allylsulfonamides are even more stringent than those which occur with the simple 5-hexenyl system.This is probably related to the shorter C-N bond distance which promotes the 5-exo trigcyclization pathway.The present method provides an attractive entry to the preparation of pyrrolidines from easily available N-(2-bromoethyl)-N-allyl- and N-(2-bromopropenyl)-N-allylsulfonamides.The method represents a clear-cut example of the use of hetero-substituted radicals in C-C bond-forming processes.

Radical cyclization as an approach toward the synthesis of pyrrolidines

Free radical cyclizations of several bromo allyl and diallyl substituted sulfonamides are described. The regiochemical course of these cyclizations depend on the nature of the substituent groups attached to the π-bond.