Hoppe coupling

H Hagenmeier, H Frank. Increased coupling yields in solid phase peptide synthesis with a modified carbodiimide coupling procedure. Hoppe-Seyler s Z Physiol Chem 353, 1973, 1972. 

Manjabacas, M.C., et al. 1995. Kinetic analysis of an autocatalytic process coupled to a reversible inhibition The inhibition of the system trypsinogen-trypsin by p-aminobenzamidine. Biol Chem Hoppe Seyler 376 577. 

In 2007, Betzer, Ardisson and co-workers reported their synthesis of discodermo-lide [64] following the Marshall disconnection strategy of C7-C8 acetylide addition and Suzuki cross-coupling at C14-05 (Scheme 32) [53, 54], The synthesis of the key subunits 160 (C1-C7), 161 (C8-C14) and 162 (C15-C24) demonstrated the versatility of the Hoppe crotyltitanation reaction [166-169] in the synthesis of polypropionate motifs, using the incorporated (Z)-0-enecarbamate to configure the requisite alkene substitution patterns [170, 171],... 

E.W. Hoppe, et al., "Use of Electrodeposition for Sample Preparation and Rejection Rate Prediction for Assay of Electroformed Ultra High Purity Copper for Th and U Prior to Inductively Coupled Plasma Mass Spectrometry," submitted for publication to J. Radioanal. Nucl. Chem., 2006. 

The authors speculate that the stereochemical divergence may be related to the ability of the electrophile to coordinate with the lithium, coupled with the presence or absence of a low-lying LUMO. Curiously, protonation by methanol proceeds with retention whereas protonation with either acetic acid or triphenyl methane proceeds with inversion. The authors speculate that, in acetic acid, protonation of the TMEDA nitrogen and internal return (c/. Schemes 3.2 and 3.24) may occur instead of direct protonation [184]. Presumably, direct protonation is the only mechanistic course with weak acids such as methanol and triphenylmethane and steric effects dictate inversion for the latter. Hoppe also noted that the enantiomeric purity of the products also depended on the solvent. In THF, the products were nearly racemic, and the enantiomeric purity of several of the other alkylation products was variable in solvents such as ether and pentane. This variability is due, at least in part, to the degree of covalency of the C-Li bond. In donor solvents such as THF, racemization is more facile. 

Cihak, A. Stability of the insoluble form of uridine kinase coupled to Zn or pb2+ ions. Hoppe-Seyler s Z. Physiol. Chem., 357, 345-350 (1976)... 

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