Acetophenones reaction with

The methylhydrazone of acetophenone (112) underwent ready reaction with n-butyl-lithium giving the dianion (113) reaction with acid derivatives such acid chlorides or esters resulted in pyrazole (114) formation whereas with aldehydes, pyrazolines were obtained (76SC5). With dichloromethyleneiminium salts (115), 5-dimethylaminopyrazoles... 

Equilibrium constants for reactions of various nucleophiles with a,a,a-trifluo-roacetophenone to give tetrahedral adducts were determined [5J] (equation 39). In the equilibria, all nucleophiles were found to be less reactive with trifluoro-acetophenone than with aldehydes [55] (equation 39). 

More recently, further developments have shown that the reaction outlined in Scheme 4.33 can also proceed for other alkenes, such as silyl-enol ethers of acetophenone [48 b], which gives the endo diastereomer in up to 99% ee. It was also shown that / -ethyl-/ -methyl-substituted acyl phosphonate also can undergo a dia-stereo- and enantioselective cycloaddition reaction with ethyl vinyl ether catalyzed by the chiral Ph-BOX-copper(ll) catalyst. The preparative use of the cycloaddition reaction was demonstrated by performing reactions on the gram scale and showing that no special measures are required for the reaction and that the dihydro-pyrans can be obtained in high yield and with very high diastereo- and enantioselective excess. 

The substitution of the lone proton on the benzhydryl carbon by a methyl group again affords compounds with antihistamine activity. Reaction of an appropriate acetophenone (21) with phenyl-magnesium bromide affords the desired tertiary alcohols (22). 

In much the same vein, the Mannich product from acetophenone with formaldehyde and pyrrolidine (44b) affords procyclidine (49) Dn reaction with cyclohexylmagnesium bromide. In an interesting variation, the ketone is first reacted with phenylmagnesium bromide. Catalytic hydrogenation of the carbinol (50) thus obtained iTin be stopped after the reduction of only one aromatic ring. ... 

Reaction of the Mannich product (112) from acetophenone itself with the Grignard reagent from p-chlorobcnzyl chloride gives the carbinol, 113. Dehydration in this case gives the antihistamine pyrrobutamine (114). It is not immediately clear why dehydration does not occur in the other sense so as to afford the energetically more favored stilbene. 

A compound closely related to classical adrenergic agonists in which the para hydroxy function is however replaced by an amino group has been investigated for its activity as a growth promoter in domestic animals. Acylation of the aniline derivative 26 with chloracetyl chloride will afford acetophenone 27 the amino-ketone 28 is obtained on reaction with isopropylamine. Removal of the protecting group (29) followed by reduction of the ketone affords cimaterol (30) 5J. 

Thus, reduction of the Mannich reaction product (65) from acetophenone leads to alcohol 66. Replacement of the hydroxyl group by chlorine (67) followed by displacement of halogen with the anion from o-cresol affords the ether 68. Removal of one of the methyl groups on nitrogen by means of the von Braun reaction or its modem equivalent (reaction with alkyl chloroformate followed by saponification) leads to racemic 69 which is then resolved with L-(+)-mandelic acid to give the levorotary antidepressant tomoxetine (69) [16]. 

Just as an aromatic ring is alkylated by reaction with an alkyl chloride, it is acylated by reaction with a carboxylic acid chloride, RCOC1, in the presence of AICI3. That is, an acyl group (-COR pronounced a-sil) is substituted onto the aromatic ring. For example, reaction of benzene with acetyl chloride yields the ketone, acetophenone. 

Phenoxy acetophenone, 46, 94 Phenylacetyleue, oxidative coupling to diphenyldiacetylene, 46, 39 partial reduction to styrene using palladium catalyst, 46, 90 reaction with sodium hypobromite to yield phenylbromoethyne, 46,86... 

Z)-3-(Tributylstannyl)allylamine participates in a palladium-catalyzed cross-coupling reaction with 2-bromobenzaldehyde (73, R = H) to give 3//-2-benzazepine (75, R = H). A similar reaction with the corresponding acetophenone 73 (R = Me) produces 1 -methyl-3//-2-benzazepine (75 R = Me), whereas with ethyl 2-bromobenzoate (73, R = OMe), 3//-2-benzazepin-(12/7)-one (74) is formed.237... 

Alkoxy-substituted allylaluminum reagents diethyl[(Z)-3-methoxy-2-propenyl]- and -[(Z)-3-(l-methoxy-l-methylethyl)-2-propenyl]aluminum have been prepared by treatment of the corresponding alkoxyallyllithiums with diethylaluminum chloride in tetrahydrofuran at — 78 =C4. These reagents provide the syn-diastereomer with 9-11 1 selectivity in reactions with aldehydes at — 78 °C. The reaction of diethyir(Z)-3-methoxy-2-propenyl]a]uminum and acetophenone provided the iy -diastereomer with 4 1 selectivity. 

Potassium or lithium derivatives of ethyl acetate, dimethyl acetamide, acetonitrile, acetophenone, pinacolone and (trimethylsilyl)acetylene are known to undergo conjugate addition to 3-(t-butyldimethylsiloxy)-1 -cyclohexenyl t-butyl sulfone 328. The resulting a-sulfonyl carbanions 329 can be trapped stereospecifically by electrophiles such as water and methyl iodide417. When the nucleophile was an sp3-hybridized primary anion (Nu = CH2Y), the resulting product was mainly 330, while in the reaction with (trimethylsilyl)acetylide anion the main product was 331. 

Substituted 6-aryl-4-methylthiopyran-2-ones may be converted into terphenyls or 4,6-diarylpyran derivatives through the carbanion induced ring-opening reaction with acetophenones <96TL93>. 

C-H insertion also occurs in the reactions with acetone and acetophenone, presumably through the rearrangement of transient OH-substituted phosphi-ranes [87]. C-C insertions occur for diketones to give 45 and have been postulated to occur via initial 1,2-addition to the conjugated enol 44 [87]. Diimines 46 also undergo C-C insertions [88]. Based on a theoretical evaluation, the products 47 are considered to result from a 2,3-sigmatropic rearrangement of initial formed P,N-ylids. 

Herrmann et al. reported for the first time in 1996 the use of chiral NHC complexes in asymmetric hydrosilylation [12]. An achiral version of this reaction with diaminocarbene rhodium complexes was previously reported by Lappert et al. in 1984 [40]. The Rh(I) complexes 53a-b were obtained in 71-79% yield by reaction of the free chiral carbene with 0.5 equiv of [Rh(cod)Cl]2 in THF (Scheme 30). The carbene was not isolated but generated in solution by deprotonation of the corresponding imidazolium salt by sodium hydride in liquid ammonia and THF at - 33 °C. The rhodium complexes 53 are stable in air both as a solid and in solution, and their thermal stability is also remarkable. The hydrosilylation of acetophenone in the presence of 1% mol of catalyst 53b gave almost quantitative conversions and optical inductions up to 32%. These complexes are active in hydrosilylation without an induction period even at low temperatures (- 34 °C). The optical induction is clearly temperature-dependent it decreases at higher temperatures. No significant solvent dependence could be observed. In spite of moderate ee values, this first report on asymmetric hydrosilylation demonstrated the advantage of such rhodium carbene complexes in terms of stability. No dissociation of the ligand was observed in the course of the reaction. 

Reaction with a benzene molecule produces acetophenone and HCl and regenerates the AICI3 catalyst. 

Enantioselective Br2 addition to cyclohexene (11) was accomplished by the solid-state reaction of a 2 1 inclusion complex of 10b and 11 with 7, although the optical yield was low (Sect. 2.1). However, some successful enantioselective solid-state reactions have been reported. For example, reaction of a 1 1 complex of 68 and acetophenone (64a) with borane-ethylenediamine complex (130) in the solid state gave the (i )-(+)-2-hydroxyethylbenzene (65a) of 44% ee in 96%... 

Carbanions derived from optically active sulfoxides react with esters, affording generally optically active )S-ketoesters ° . Kunieda and coworkers revealed that treatment of (-t-)-(R)-methyl p-tolyl sulfoxide 107 with n-butyllithium or dimethy-lamine afforded the corresponding carbanion, which upon further reaction with ethyl benzoate gave (-l-)-(R)-a-(p-tolylsulfinyl)acetophenone 108. They also found that the reaction between chiral esters of carboxylic acids (R COOR ) and a-lithio aryl methyl sulfoxides gave optically active 3-ketosulfoxides The stereoselectivity was found to be markedly influenced by the size of the R group of the esters and the optical purity reached to 70.3% when R was a t-butyl group. 

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