L-Tyrosine hydrazide

Product Analysis. The distilled product is dissolved in 2 mL of dry methylene chloride and an internal standard is added (naphthalene for 4-phenyldeltacyclene, biphenyl for 4-n-butyldeltacyclene). The chemical yield and the enantiomeric excess of the product can be determined by GLC using a 40 m column of perpentylated p-cyclodextrin. 4-Phenyldeltacyclene column temperature 104 °C, retention time (—)-isomer 124.7 min, (+)-isomer 128.2 min 4-n-butyldeltacyclene column temperature 65 °C, retention time (—)-isomer 78.3 min, (+)-isomer 80.8 min. 

For 4-n-butyldeltacyclene, no other cocatalyst gives the quantitative yield and 98-99% enantiomeric excess observed in the NORPHOS-containing system. The PROPHOS system gives 80% enantiomeric excess. 

Variation of the Procatalyst (Metal Component) and the Acetylenic Substrate. The in situ catalysts Co(acac)3-Et2AlCl-phosphine have proven to be well-suited for the synthesis of 4-aryl- and 4-alkyl-substituted deltacyclenes. The catalysts tolerate remote oxygen functionalities in the acetylenic substrate. However, they could not be used with functionalized acetylenes such as propargylic acid derivatives. 

Schneider, A. Chem. Commun./J. Chem. Soc., Chem. Commm. Wti, 636. 

Solubility slightly sol cold methanol or ethanol readily sol hot methanol or ethanol. 

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The Z-protected derivative, again prepared by standard methods using benzyl chloroformate,t208 may serve in the case of racemic pipecolic acid for resolution into the pure enantiomers by fractional crystallization with L-tyrosine hydrazide/208 Acylation with N-protected pipecolic acid or of pipecolyl peptides is performed by standard procedures via the active ester methods, e.g. A-hydroxysuccinimide ester/121 by the mixed anhydride method, e.g. with isobutyl chloro-formate 95-114 or pivalic acid chloride/121 as well as by DCC/HOBt/118 In the synthesis on solid support, longer coupling times are required when compared to N-protected proline.1[235 ... 

Preparative Methods the synthesis of L-tyrosine hydrazide from L-tyrosine has been described. o-Tyrosine hydrazide has been obtained by resolution of oL-tyrosine hydrazide with Cbz-L-proline. ... 

Fig. 1 Dependence of k on adrenaline (squares) and L-tyrosine hydrazide (circles), on mobile-phase concentration of 1-hexane-sulfonate. Column Synergi Hydro-RP (Phenomenex) 150 x 4.6 mm ID, particle size 4 pm, and bonded phase coverage 4.05 pmol/m. Eluent phosphate buffer 37.10 mM KH2PO4 and 4.29 mM Na2HP04 calculated to provide a pH of 6.0. After addition of the desired amount of sodium 1-hexanesulfonate, NaCl was added so that the total sodium concentration was 50 mM (constant ionic strength). Experimental data were fitted by Eq. 8.

Fig. 2 Dependence of k on adrenaline (squares) and L-tyrosine hydrazide (circles), on stationary-phase concentration of 1-hex-anesulfonate. Conditions as in Fig. 1. Experimental data were fitted by Eq. 9.

Resolution The carbobenzoxy derivatives of DL-proline, DL-alanine, and dl-isoleucine have been resolved by fractional crystallization, in the lower alcohols or water, of the diastereoisomeric salts with L-tyrosine hydrazide. The yield is low in the case of DL-phenylalanine. 

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