Phenylmenthyl Crotonate

A Lewis acid-mediated two-fold asymmetric Michael addition allows access to c( s-decalin derivatives. The reaction of the trimethylsilylenol ether of acety Icyclohexene with phenylmenthyl acrylate in the presence of Diethylaluminum Chloride (eq 7) yields the decalone in 64% yield (70% de). This has been shown not to be a Diels-Alder reaction. If the reaction is worked-up early, the initial Michael adduct can be isolated.  

Phenylmenthyl acrylate has been used as a component in an asymmetric Baylis-Hillman reaction. Treatment of the acrylate with 1,4-Diazabicyclo[2.2.2]octane and benzaldehyde at 8 kbar of pressure delivers the a-(hydroxyalkyl)acrylate (eq 8). The product obtained has an 86% de. Menthyl acrylate is superior to the phenylmenthyl acrylate in this particular application. In a radical-mediated addition, phenylmenthyl acrylate gives rise to the a-pyridyl sulfide in 68% yield (eq 9). The final product is isolated with a 56% de. 

Miscellaneous. The acrylate provides a synthon for the preparation of 8-Phenylmenthyl Glyoxylate, which is useful for asymmetric ene reactions. Thus ozonolysis and remoeval of the water of hydration produces the glyoxylate in 89% yield (eq 10). 

Oppolzer, W. Kurth, M. Reichlin, D. Chapius, C. Mohnhaupt, M, Moffatt, E Helv. Chim. Acta 1981, 64, 2802. 

(a) Clark, C. Hermans, R Meth-Cohn, O. Moore, C. Taljaard, H. C, van Vuuren, G, Chem. Commun./J. Chem. Soc., Chem. Commun. 1986, 1378. (b) Meth-Cohn, O. Moore, C. Taljaard, H. C. J. Chem. Soc., Perkin Trans. I 1988, 2663. 

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Chiral fl-amino esters. The conjugate addition of primary amines to alkyl crotonates proceeds in satisfactory yield when carried out under high pressure. French chemists have recently examined this reaction using crotonates derived from chiral alcohols. Thus addition of diphenylmethylamine to 8-phenylmenthyl croton-ate proceeds in 85-90% chemical yield and in 60% de. Optical yields are increased... 

Asymmetric Michael addition to enoatesThe known conjugate addition of RCu BF, (8, 324-325) to a,/(-unsaturated carbonyl compounds4 proceeds with high chiral induction to trans- )-8-phenylmenthyl crotonate (2). Addition to the isomeric ei.v-crotonate (5) is less selective, but results mainly in the enantiomeric acid (6). 

Phenylisoxazoline-3-ones, 312 8-Phenylmcnthol, 412-415 8-Phenylmenthyl crotonate, 412. 413 Phenylmercuric hydroxide, 415 Phenylmercuric perchlorate, 415-416 C-Phenyl-N-methylnitrone, 538, 539... 

Related Reagents. 8-Phenylmenthyl Crotonate 8-Phenyl-menthyl Glyoxylate 8-Phenylmenthyl Pyruvate. 

Hydroperoxide-n-Butyllithium gives 50% de. Chiral 3-amino esters of 8-phenylmenthol have been prepared in 50-60% de by the addition of amines to the re face of 8-phenylmenthyl crotonate under 14-15 kbar pressures (eq 2). Much higher (75 to >99%) de is obtained using 8-0-naphthyl)menthol crotonate. The 3-amino esters obtained are of the proper configuration for conversion to biologically active 3-lactams. ... 

Some of the Lewis acid catalyzed Michael additions to a,3-unsaturated carbonyls can also be rationalized based on these models. For example, BFs-mediated additions of organocopper reagents to chiral a,3-unsaturated esters such as (-)-8-phenylmenthyl crotonate (35) occur with high levels of dia-stereoselectivity. " The product stereochemistries for these reactions could be predicted by assuming the reactive conformation (35S), which follows the basic structural tenets of model A (Figure 41). ... 

Aside from Coreys phenylmenthyl propanoate 424, several chiral enolates have been utilized for Michael additions with substantial degrees of diastereoselectiv-ity. Yamaguchi s group developed a series of chiral amide enolates 436 and studied the conjugate addition to crotonates [210]. Another remarkable early contribution came from Oppolzer and coworkers who used dienolate 437 for diastereoselec-tive consecutive additions to cyclopentenone and allylation [211]. The auxiliaries 436 and 437 served for total syntheses of terpenoid natural products. Diastereos-elective Michael additions were also achieved by means of imidazolidinone-based lithium enolate 438 [212] - another showcase of the efficiency of imidazolidinone 118 [54] (Scheme 4.94). 

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