Trimethylsilyl esters acid halide synthesis

Sodium bis(trimethylsilyl)amide a-Aminocarboxylic acid esters from halides Synthesis with addition of 2 C-atoms... 

New routes to phosphoenolpyruvic acid (PEP) which have been explored involve the dealkylation of both phosphoric and carboxylic acid esters by trimethylsilyl halides, and are summarized in Scheme 2. The immediate precursor to the PEP is the tris(trimethylsilyl) ester (18) initial attempts to obtain this from ethyl bromopyruvate failed because the ester (16) could not be further silylated through de-ethylation. However, a synthesis of (18) from... 

Formation and Reaction of the Trimethylsilyl Ester of Squaric Acid. The most common method employed in the synthesis of squarate esters uses expensive silver nitrate and goes through the explosive disilver salt of squaric acid. It was conceived that sUyl esters of squaric acid 38 may be considered as silyl enol ethers that can undergo Si-O cleavage in the presence of a suitable fluoride source and that O-alkylation may be affected using electrophilic halides. Upon preparation of thebis(trimethyl-silyl) squarate 39 using BSA and reaction in situ with p-methylbenzyl bromide in the presence of a fluoride source, the desired benzyl squarate 40 was obtained in about 50% overall yield (eq 42). ... 

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

Reaction of a,j5-unsaturated aldehydes with diethyl trimethylsilyl phosphite was used for the synthesis of chain-lengthened esters. Alkylation of the a-silyloxy-j ,y-unsaturated phosphonate with lithium diisopropylamide (Ida) and an alkyl halide occurs at the y-position with migration of the double bond to the a,j9-position. The silyloxyenolate could isolated in this reaction. Acide-catalysed alcoholysis leads to the carboxylic ester through the acylphosphonate (equation 93) ". ... 

Methanesulfonates. The most common use of methanesulfonyl chloride is for the synthesis of sulfonate esters from alcohols. This can be readily accomplished by treatment of an alcohol with mesyl chloride in the presence of a base (usually Triethy-lamine or Pyridine). The methanesulfonates formed are functional equivalents of halides. As such they are frequently employed as intermediates for reactions such as displacements, eliminations, reductions, and rearrangements. Selective mesylation of a vicinal diol is a common method of preparation of epoxides." Alkynyl mesylates can be used for the synthesis of trimethylsilyl allenes. Oxime mesylates undergo a Beckmann rearrangement upon treatment with a Lewis acid. Aromatic mesylates have been used as substrates for nucleophilic aromatic substitution. Mesylates are more reactive than tosylates toward nucleophilic substitution, but less reactive toward solvolysis. 

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