Related reagents acid chlorides

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... 

Method A reaction of a 2-hydrazinopyrimidine with acid chloride or related reagent. Method B reaction of a hydrazone by oxidizing agent (e.g., bromine, ferric chloride). 

Acylation reactions can also be greatly improved in this way, with t-alkyl- or sec-alkyl-manganese reagents reacting with acid chlorides in excellent yields [123]. The related addition-elimination to 3-ethoxy-2-cyclohexenone is also improved, resulting after acidic aqueous workup in 3-methyl-2-cyclohexenone [125]. The perilla-ketone 126 was prepared in an improved yield using copper(I) catalysis (Scheme 2.58) [129]. 

Much the same activity is retained when the nitrogen atoms in the heterocyclic nucleus are shifted around. The convergent scheme to this related compound starts with the acylation of alanine (35-1) with butyryl chloride (35-2). The thus-produced amide (35-3) is then again acylated, this time with the half-acid chloride from ethyl oxalate in the presence of DMAP and pyridine to afford the intermediate (35-4). In the second arm of the scheme, the benzonitrile (35-5) is reacted with the aluminate (35-6), itself prepared from trimethyl aluminum and ammonium chloride, to form the imidate (35-7). Treatment of this intermediate with hydrazine leads to the replacement of one of the imidate nitrogen atoms by the reagent by an addition-elimination sequence to form (35-8). Condensation of this product with (35-4) leads to the formation of the triazine (35-9). Phosphorus oxychloride then closes the second ring... 

Please note that this whole section—indeed all of the chapter so far—relates to the C-C disconnection between the carbonyl group and whatever is joined to it 2. The nucleophilic reagent is an organometallic derivative of Li, Cu or Mg and the electrophile is an acid chloride, a tertiary amide or a nitrile. In the next section we disconnect the C-C bond one further from the carbonyl. 

Other related species, such as alkyl chloroformates183, dialkyl carbamyl chlorides1, 77-aryl iminoyl chlorides184 or N-substituted isocyanide dichloride (with alkynyl stannanes only)185 behave in an analogous manner. Acylation of acid chlorides has even proven to be possible with acyltin reagents, or by dimerization of acid chlorides with hexabutylditin and high CO pressure186. 

The esters were prepared from the phenol and the acid chloride plus DM AP (or from the acid plus trifluoroacetic anhydride). In these esters the steric hulk of the ortho substituents protects the carhonyl from nucleophilic reagents, making them difficult hydrolyze. Although the diisopropyl derivative can be cleaved with hot aqueous NaOH, the di-f-butyl derivatives could only be cleaved with NaOMe in a mixture of toluene and HMPA. The related 2,6-di-f-butyl-4-methoxyphenyl ester can be cleaved oxidatively with ceric ammonium nitrate. These hindered esters have found utility in directing the aldol condensation. ... 

All the syntheses published for the oxadiazolo- and thiadiazolo[3,2-fl][l,3,5]triazine ring systems ((10) and (13), respectively) utilize the ring closure possibility of ureido or thioureidoazoles by acid chlorides or related reagents. 

In related work, rapid synthesis of 1,2,4-oxadiazoles was achieved on polymer-supported reagents [109]. Two independent pathways were used to prepare these heterocycles from carboxylic acids and amidoximes under the action of microwave irradiation. In accordance with the conventional method using HBTU and N,N-diisopropylethylamine (DIEA) for synthesis of this heterocycle, a method utilizing polymer-supported bases was employed. The use of PS-BEMP in the presence of HBTU proved to be beneficial in the microwave procedure. Heating for 15 min in acetonitrile at 160 °C furnished high yields for a series of substrates. 1,2,4-Oxadiazoles can also be synthesized from carboxylic acid chlorides. Because these... 

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