Nucleophile-catalyzed

The arylation of the nucleophiles catalyzed by the same catalyst or another one takes place and shifts the equilibrium by consuming the iodobenzene and regenerating the iodide. 

Fig. 23. Reactions of bromoarenes with hard (and soft) nucleophiles catalyzed by nickel, copper and palladium...

Wilson JE, Fu GC (2004) Asymmetric synthesis of highly substituted P-lactones by nucleophile-catalyzed [2 -t 2] cycloadditions of disubstituted ketenes with aldehydes. Angew Chem Int Ed 43 6358-6360... 

Mermerian AH, Fu GC (2005) Nucleophile-catalyzed asymmetric acylations of silyl ketene imines application to the enantioselective synthesis of verapamil. Angew Chem Int Ed 44 949-952... 

Let us return now to a brief further consideration of the acid- and nucleophile-catalyzed reactions of thiosulfinates. We have seen that in the various acid- and nucleophile-catalyzed reactions of PhS(0)SPh the attack of... 

Much attention has been devoted to the acid- and nucleophile-catalyzed racemization of thiosulfinates. As a result of the extensive studies by Kice and his co-workers (112) and by Fava (281), it is clear now that the easy racemization of thiosulfinates caused by acids and bases (e.g., pyridine) is related to the scission of the sulfur-sulfur bond and the formation of sulfenic acid or its anion as an achiral intermediate. As expected, introduction of steric hindrance... 

Several types of intramolecular allylic substitution reactions of carbon, nitrogen, and oxygen nucleophiles catalyzed by metalacyclic iridium phosphoramidite complexes have been reported. Intramolecular allylic substitution is much faster than the competing intermolecular process when conducted in the presence of iridium catalysts. Thus, conditions involving high dilution are not required. Intramolecular... 

The mechanism by which chiral nucleophiles catalyze asymmetric acyl transfer in the KR of, yec-alcohols can be seen as a three-step process (Scheme 1) [2]. 

Scheme 18 Bifunctional Lewis acid/nucleophile catalyzed synthesis of P-lactams...

Scheme 19 Diastereoselectivity in the nucleophile-catalyzed reaction of methylphenylketene and imine...

It is worthy of note that the type of reaction shown in Scheme 6.39, Eq. (1) was reported only recently [102]. In 2001, Romo and co-workers described an intramolecular, nucleophile-catalyzed aldol-lactonization (NCAL) process which contains... 

Kaneda K, Kurosaki H, Terasawa M, Imanaka T, Teranishi S (1981) Selective telomerization of butadiene with various nucleophiles catalyzed by polymer-bound palladium(O) complexes. J Org Chem 46 2356-2362... 

The nucleophile-catalyzed aldol lactonization (NCAL) reaction of carboxyl-derived zwitterions and unactivated aldehydes has been applied to the catalytic asymmetric synthesis of bicyclic /3-lactones (Equation 31)... 

There is also a well-documented mechanism of nucleophile-catalyzed racemization of silane that does not involve an ionic intermediate. This mechanism operates in at least some peculiar classes of cyclic silanes, having particular ability to form complexes with nucleophiles. Stevenson and Martin (287) studied carefully the kinetics of the inversion of a bicyclic spirosilane A [Eq. (70)]. The reaction was catalyzed by a weak nucleophile, a substituted benzaldehyde. The mechanism consistent with... 

In conclusion, studies of nucleophile-catalyzed inversion at the silicon center point to various mechanistic possibilities of this transformation. Results of such studies also support the role of silylonium ions as intermediates. 

Substoichiometric loadings of DBU catalyze the efficient 1,4-addition of nonnucleophilic amines such as pyrrole to activated alkenes. A novel and efficient nucleophile-catalyzed N-cyanoethylation of pyrrole (pK 16.5) gives pyrrol-l-yl)propanenitrile 142 in good yield (Scheme 30) <2005CC227>. 

The ion pairs on the right side of equation (148) may dissociate into R2S2, R2S4, and Rs P, and the formation of tetrasulfane was observed. In other words, tertiary phosphanes (including Ph3P), like other strong nucleophiles, catalyze the exchange and interconversion (equations 149 and 150), which has been observed. ... 

Aziridines bearing an acyl substituent on the 1-position of the ring are particularly prone to isomerization both thermally by a unimolecular process and in a characteristic nucleophile catalyzed bimolecular process. The products of the... 

On the other hand, linear products rather than branched isomers were obtained in the allylic alkylation of l-aryl-2-propenyl acetates and 3-phenyl-2-propenyl acetate with soft carbon nucleophiles catalyzed by the Pd/PPh3 system when a catalytic amount of Lil was used [38]. 

The mechanism of the amines or alcohols arylation catalyzed by nickel(II) complexes has not been elucidated until now (refs. 7, 17), even though the arylation of nucleophiles catalyzed by nickel(0) complexes is better understood. In this last case it is generally admitted that the reaction proceeds by an oxidative addition step, followed by a nucleophilic substitution, and then a reductive elimination of the arylation product (Scheme 4). According to the work of Kochi (ref. 18), the oxidative addition of the haloarene on a nickel(O) complex takes place through a monoelectronic transfer from the metal to the aryl halide with simultaneous formation of a nickel(I) intermediate, the actual catalyst of the reaction (ref. 6). 

Scheme 4. Attempted mechanism for the arylation of hard nucleophiles catalyzed by Ni(0) complexes.

SCLCPs have also been prepared by group transfer polymerization (GTP) of mesogenic methacrylates are room temperature [47, 48]. The livingness of the nucleophilic catalyzed GTP was originally attributed to a new mechanism (Eq. 12), in-... 

Wang et al. have developed a new one-pot procedure for the sequential Morita-Baylis-Hillman and Michael additions to construct two carbon-carbon bonds with aromatic aldehyde, a,p-unsubstituted acrylate and a methide nucleophile catalyzed by DBU. This one-pot procedure will provide a useful tool for generating highly functionalized and diversified organic molecules (Scheme 3.208). " ... 

Summary MesGeSiCls is a useful new source for the nucleophile-catalyzed generation of SiCl2 under very mild conditions. 

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