Propanoyl chloride acylation with

What is an immediate precursor of propiophenone " Benzene, which could undergo Friedel-Crafts acylation with propanoyl chloride and AlClv... 

Alternatively, the imide-acid chloride is reacted with methanol to give the imide ester which, after borohydride reduction and triethylsilane/trifluoroacetic acid treatment, furnishes the bicyclic lactam 6 as a racemate. The latter is acylated with either propanoyl chloride or 3-phcnylpropanoyl chloride and the resulting amides 7 deprotonated and alkylated with (bro-momethyljbenzene or iodomethane, respectively, to give the major alkylation products 8 with d.r. >98 2 and in 65% yield3. 

Racemic l-dimethylaminopropan-2-ol (18) was acylated with propanoyl chloride, and the reaction product was analyzed by gas chromatography (GC). The resultant (R)- and (5)-esters 19 (R1 = COEt) were resolved by GC using an a-cyclodextrin column. Reaction of the racemic alcohol 18 was then carried out in the presence of Novozyme 435 and vinyl propanoate, and the reaction was followed by GC. After 4 hours the reaction was approximately 2% complete and the ee of the propanoate ester 19 (R1 = COEt) was 95.9%. After 88 hours the conversion had reached 50% and the ee was still 95.6%. The remarkable specificity of Novozyme 435 for the (/O-amino alcohol 1 A )-18 was evident because even after 3.5 days reaction time, only a very small amount of the (5)-ester was detected. The reaction could be scaled up thus, 1 kg of the racemic amino alcohol 18 was treated with vinyl propanoate (0.5 equivalents) and Novozyme 435 (3% by weight). After 3 days, both optically active products were isolated by distillation at reduced pressure. The (5)-amino alcohol (.V)-18 was recovered in 45% yield, which compared favorably with a yield of 32% for resolution on a small scale. The (R)-propanoate 19 (R1 = COEt) distilled as a colorless oil in 36% yield — slightly higher than that obtained from the small-scale resolution. The overall recovery was 81% from the scaled up reaction. 

This two-step sequence can synthesize many alkylbenzenes that are impossible to make by direct alkylation. For example, we saw earlier that n-propylbenzene cannot be made by Friedel-Crafts alkylation. Benzene reacts with n-propyl chloride and AICI3 to give isopropylbenzene, together with some diisopropylbenzene. In the acylation, however, benzene reacts with propanoyl chloride and A1C13 to give ethyl phenyl ketone (propiophenone), which is easily reduced to n-propylbenzene. 

Preparation and Stability. Since A -unsubstituted oxazo-lidines are labile to hydrolysis, they should be transformed immediately after preparation to amide derivatives, which show much higher stability. Thus reaction of (S)-3-amino-2-methyl-4-phenyl-2-butanol with acetone in the presence of a catalytic amount of p-Toluenesulfonic Acid produces (S)-4-benzyl-2,2,5,5-tetramethyloxazolidine. A -Acylation using acryloyl, cinnamoyl, and propanoyl chloride (Et3N, —78°C) gives the corresponding amides. The 7V-crotonoyl derivative is better obtained by the crotonoylation of (S)-3-amino-2-methyl-4-phenyl-2-butanol followed by acetalization with (Me)2C(OMe)2. 

The same catalyst promotes the reaction of toluene and anisole with propanoyl chloride the acylation product 42 (Ri = OMe = Me) and... 

Phenol undergoes propanoylation with propanoyl chloride over BEA, Y, MOR, and ZSM-5 zeolites The main product is phenylpropanoate moreover, BEA (Scheme 5.7) is the most active in the C-acylation and selective for para-hydroxypropiophenone production (ortho/para = 0.53) compared to other zeolite catalysts. 

R - C = 0. Once formed, the acylium ion undergoes an electrophilic aromatic substitution reaction with the aromatic compound. The product of this acylation reaction is an aromatic ketone. Toluene is acylated by propanoyl chloride to give both ortho and para substituted products. 

As actually carried out, the chiral auxiliary was acylated at nitrogen with propanoyl chloride and the propanoyl group then deprotonated at its a carbon with lithium diiso-propylamide forming an enolate. 

By contrast, the Friedel-Crafts acylation of benzene with propanoyl chloride produces a ketone with an unrearranged carbon chain in excellent yield ... 

Several examples can serve to illustrate the use of chiral auxiliaries. First, the chiral, heterocyclic, amino-add-derived lactam, (5)-4-(phenylmethyl)-2-oxazolidinone, is capable of conversion into an anion on treatment with butyllithium [CH3(CH2)2CH2Li]. Acylation at nitrogen with propanoyl chloride produces chiral propionamide. 

Acylium ions produced in the Friedel—Crafts reaction do not rearrange. The acyl group in the product can be reduced using a zinc—mercury amalgam and HCl to produce an alkylbenzene. This reaction is called a Clemmensen reduction. This circumvents the rearrangement of primary alkyl groups that occurs in the Friedel—Crafts alkylation reaction. For example, acylation of benzene with propanoyl chloride followed by a Clemmensen reduction yields propylbenzene. 

As we saw on page 396, an acyl chloride is similar in structure to a carboxylic acid, with the —OH group replaced by a Cl atom. So the —COOH functional group is changed to the —COCl group. The structural formula of acyl chlorides can be written as ROCl, where R is an alkyl or aryl group. For example, propanoyl chloride can be written as CHjCH COCl. 

Examples of C- or N- acylations of the 1,2,6-thiadiazine 1,1-dioxide nucleus are rare. However, acylation of 2,6-dimethyl-4//-l,2,6-thiadiazine-3,5(2H,6//)-dione 1,1-dioxide (140 R = Me) with propionyl chloride in acetonitrile in the presence of triethylamine and magnesium chloride affords the 4-propanoyl derivative (141) (Scheme 10) <89BRP2213145>. 

The most prominent cellulose ester produced on the industrial scale is cellulose acetate. The reaction is usually performed with acetic anhydride and with sulfuric acid as a catalyst. To minimize heterogeneities, acetylation is allowed to run nearly to completion, and subsequently partial ester hydrolysis is initiated by the addition of water until a desirable solubility is achieved that corresponds to a DS of about 2.5. Such higher acyl homologues as propanoyl or butanoyl exhibit more thermoplastic properties. Many specialized esters such as chiral (-)-menthyloxyacetates, furan-2-carboxylates, or crown-ether-containing acylates have been prepared on the laboratory scale and characterized by NMR spectroscopy. Various procedures have been applied, using anhydrides and acyl chlorides as acylating agents in combination with such bases as pyridine, 4-dimethylaminopyridine (DMAP), or iV,iV -carbonyldi-imidazole. The substitution pattern of cellulose acetates has also been modified by postchemical enzymatic deacetylation. Cellulose 6-tosylates have been used as activated intermediates for nucleophihc substitution to afford 6-amino-6-deoxy, 6-deoxy, or 6-deoxy-6-halo-celluloses. ... 

---