Carbonyl groups, pendant

The reaction is based upon the two components condensation between an aldehyde or ketone 6 (or their synthetic equivalents) and alcohol 95, which contains an allylsilane (or vinylsilane) moiety. The IMSC reaction is mediated by Lewis or Bronsted acids, which activate the carbonyl group of 6 towards nucleophilic attack. After addition of alcohol 95 on the activated carbonyl, the oxonium cation 96 is formed, which is intramolecularly captured by the pendant allylsilane function, leading to oxygen-containing rings 97 (Scheme 13.38). This process typically requires a stoichiometric (or more) amount of Lewis acid. 

T he free radical initiated polymerization of polar monomers containing pendant nitrile and carbonyl groups—e.g., acrylonitrile and methyl methacrylate—in the presence of metal halides such as zinc chloride and aluminum chloride, is characterized by increased rates of polymerization (2, 3, 4, 5,10, 30, 31, 32, 33, 34, 53, 55, 65, 66, 75, 76, 77, 87). Imoto and Otsu (30, 33, 34) have attributed this effect to the formation of a complex between the polar group and the metal halide. The enhanced reactivity of the complexed monomer extends to copolymerization with uncomplexed monomers, such as vinylidene chloride, which are readily responsive to... 

The blends of polysulfone with the a-methyl styrene polymers are immiscible, as evidenced by the double glass-transition temperatures in Table II. To improve the miscibility characteristics, polysulfone was modified in two ways. First, 25% of the bisphenol A was replaced by monomer I which contains a pendant ester group and, when no improvement resulted, the whole 50% of the bisphenol A was replaced. Again, the blends remain immiscible as evidenced from Figures 4 and 5 and from Table II. Further, the presence of the pendant ester group in polymer C does not improve the miscibility picture even though one would expect a favorable contribution from the carbonyl group on account of the miscibility of polycarbonate with the a-methyl styrene polymers. 

When the labilities are reversed, that is when the NHC group is used as the anchor, ligand design again orientates itself on the successful hemilabile bidentate phosphanes. Now, we encounter pendant ether [34,35], tertiary amino [36,37], pyrido [11,38 0], imino [41-44] and carbonyl groups [30,45] in the sidechain. 

Both semiproducts with a pendant arm macrocyclic structure undergo macrocyclization in neutral solution via a Nef reaction intermediate step with detachment of a NO species, followed by condensation of the resulting carbonyl group with a deprotonated and coordinated primary amino group [106]. 

The copolymerization of ethene and CO produces an interesting polar material with alternating C2 alkane and carbonyl groups. If a monosub-stituted alkene is used, isotactic and syndiotactic polymers can result. The usual catalyst for such a process is a Pd-phosphine complex. If the phosphine ligand is chiral, stereoregularity with reference to the pendant group from the alkene can result. 

If the Staudinger reaction of an alkyl azide containing a pendant carbonyl group is heated under anhydrous conditions, the iminophosphorane can nucleophilically attack the carbonyl leading to cyclic imines (via the aza-Wittig mechanism) and liberate phosphine oxide as shown below. The reaction also works intermolecularly. 

Bonjoch has just begun to explore a novel intramolecular annulation of 2-haloanilines with pendant ketones 95 which can lead to indolic products 96 by either of two different and competitive cyelization pathways, namely, enolate arylation or addition of the organometallic intermediate to the ketone carbonyl group <01CC1888>. 

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