Phenylmenthyl Pyruvate

Cervinka, O. Svatos, A. Trska, P, Pech, P. Collect. Czech. Chem. Commun. 1990, 55, 230. 

(a) Yamamoto, Y Maeda, N. Maryuma, K. Chem. CommunJJ. Chem. Soc., Chem. Commun. 1983, 774. (b) Yamamoto, Y Yatagai, H. Ishihara, Y Maeda, N. Maryuma, K. Tetrahedron 1984,40, 2239. 

Apurba Bhattacharya Hoechst-Celanese Corporation, Corpus Christi, TX, USA 

Alternate Name (17 ,2S,5/ )-5-methyl-2-(l-methyl-l-phenyl-ethyl)cyclohexyl pyruvate. 

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Chiral Auxiliary for Asymmetric Induction. Numerous derivatives of (—)-8-phenylmenthol have been utilized for asymmetric induction studies. These include inter- and intramolecular Diels-Alder reactions, dihydroxylations, and intramolecular ene reactions of a,p-unsaturated 8-phenylmenthol esters. These reactions usually proceed in moderate to good yield with high diastereofacial selectivity. a-Keto esters of 8-phenylmenthol (see 8-Phenylmenthyl Pyruvate) have been used for asymmetric addition to the keto group, as well as for asymmetric [2 -F 2] photoadditions and nucleophilic alkylation. Ene reactions of a-imino esters of 8-phenylmenthol with alkenes provide a direct route to a-amino acids of high optical purity. Vinyl and butadienyl ethers of 8-phenylmenthol have been prepared and the diastereofacial selectivity of nitrone and Diels-Alder cycloadditions, respectively, have been evaluated. a-Anions of 8-phenylmenthol esters also show significant diastereofacial selectivity in aldol condensations and enantiose-lective alkene formation by reaction of achiral ketones with 8-phenylmenthyl phosphonoacetate gives de up to 90%. ... 

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

Reduction of 8-phenylmenthyl pyruvate with Potassium Triiso-propoxyborohydride in THF gives 90% de of the (R)-lactate ester (eq 2), but other reducing reagents show little selectivity. The stereochemical outcome of this reduction is explained as occurring in the s-trans conformation of the pyruvate. 

Thermal ene reaction of -pinene with methyl pyruvate provides a 1 1 mixture of endo and exo ene adducts. This reaction can also be carried out in quantitative yield at 40 kbar for 17 h at 25 Contrary to a published report 8-phenylmenthyl pyruvate does not undergo a Lewis acid catalyzed ene reaction with 1-hexene. However, reaction of rra/u-2-phenylcyclohexyl pyruvate with 1-hexene and 2 equiv. of TiCU for 15 min at 0 C affords a 15 1 mixture in 85% yield of ene adduct (74) in 86% dia-stereomeric excess and tetrahydrofuran (75) derived from (74) by protonation of the double bond and cy-clization. 

Allylations. In reactions using most popular catalysts. It is now et 8-phenylmenthyl pyruvate, and. V-j that the four stereocenters of the pro and two aldehyde molecules are get intramolecular reaction is most suiu lactones. ... 

Allylations. In reactions using allylsilane as nucleophiles TiCU is one of the most popular catalysts. It is now employed in allylating squaric acid derivatives, 8-phenylmenthyl pyruvate, and (V-acyliminium ions. A remarkable observation is that the four stereocenters of the products from l,8-bis(trimethylsilyl)-2,6-octadiene and two aldehyde molecules are generated with good control. The stereoselective intramolecular reaction is most suitable for the synthesis of bicyclic a-methylene-y-lactones. ... 

Tin(IV) Chloride-catalyzed ene reaction of the pyruvate ester of (—)-8-phenylmenthol with 1-hexene gives a single diastereomer of the unsaturated (S)-a-hydroxy ester (de>90%) (eq 3). Similarly, tin(I V) chloride-catalyzed ene reactions of 8-phenylmenthyl glyoxylates afford unsaturated secondary alcohols with 93-98% de of the (S) configuration. ... 

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