Acid anhydrides reactions with organometallic

Furthermore reactions with difluorophosphoric anhydride are of some importance (55). The easy cleavage of the P—0—P-bridge in reactions with organometallic oxides (17) and halides (18) leads to derivatives of difluorophosphoric acid in a very mild way ... 

Diphenylphosphinic mixed anhydrides have been utilized to form peptide bonds. Peptides are easier to isolate by this method than by employing 1,3-Dicyclohexylcarbodiimide. These anhydrides are the method of choice for the formation of amides of 2-alkenoic acids (eq 1 ). Carbodiimide and acyl carbonate methods proved to be inferior. Primary amines result in better yields than secondary amines. This activation protocol can be employed to form thiol esters (eq 2) p-Amino acids are readily converted to p-lactams with chlorodiphenylphosphine oxide (eq 3). Secondary amines work best. This activation protocol has been utilized to convert acids to amines via a Curtius rearrangement. Phenols have been generated from diene acids, presumably via base-induced elimination of diphenylphosphinic acid from the mixed anhydrides to form ketenes which spontaneously cyclize. Acids have been converted to ketones via activation followed by reaction with organometallic reagents (eq 4)."... 

Volume 15 deals with those polymerization processes which do not involve free radicals as intermediates. Chapters 1 and 2 cover homogeneous anionic and cationic polymerization, respectively, and Chapter 3 polymerizations initiated by Zeigler-Natta and related organometallic catalysts. Chapters 4, 5 and 6 deal with the polymerization of cyclic ethers and sulphides, of aldehydes and of lactams, respectively. Finally, in Chapter 7 polycondensation reactions, and in Chapter 8 the polymerization of AT-carboxy-a-amino acid anhydrides, are discussed. 

This chapter will discuss methods for the preparation of esters, acid chlorides, anhydrides, and amides from carboxylic acids, based on acyl substitution reactions. Acyl substitution reactions of carboxylic acid derivatives will include hydrolysis, interconversion of one acid derivative into another, and reactions with strong nucleophiles such as organometallic reagents. In addition, the chemistry of dicarboxylic acid derivatives will be discussed, as well as cyclic esters, amides, and anhydrides. Sulfonic acid derivatives will be introduced as well as sulfate esters and phosphate esters. Finally, nitriles will be shown to be acid derivatives by virtue of their reactivity. 

Entries 3 and 4 are acylahon and alkylation, respectively, of hydroxyl groups. Entry 3 shows the formation of a pentaacetate on reaction of a-D-glucopyranose with acetic anhydride, and entry 4 shows the formation of a tetrabenzyl ether on reachon of methyl a-D-glucopyranoside with benzyl chloride. Benzyl ethers are stable to acid and base hydrolysis, organometallic reagents, and numerous other reaction conditions and are often used to protect... 

Boroxines result from the condensation of boronic acids. RBfOH). The cyclic Irimeric anhydride of methylboronic acid is (IVfeBO),. Give a balanced equation for the reaction of (MeBO)j with water (See Brown, H. C. Cole, T. E. Organometallics 1985.4. 816.)... 

Discovered by Thorn and first communicated only a few years ago [43], electrophilic aromatic stannylation is the newest of all metalation reactions described in this chapter. The reactive Sn electrophile can be prepared by dearylation of Ph4Sn with TFAH or, preferably, by reaction of SnO with trifluoroperacetic acid generated from H202, TFAH, and trifluoroacetic anhydride. Because the structure of the Sn(IV) species (or mixtures of species) produced this way is unknown, the reactive electrophile is depicted as Sn(TFA)4 , for simplicity. The stannylation reactions of benzene and p-xylene were shown to produce tetratin clusters containing two inorganic and two organometallic Sn centers (Scheme 7). 

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