Rational Development of Practical Catalysts for Aromatic Carbon−Nitrogen Bond Formation

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

A series of C2-symmetric chiral quaternary ammonium bromides 10 and 11 have been designed as a new, purely synthetic chiral phase-transfer catalyst, and readily prepared from commercially available optically pure 1,1‘-bi-2-naphthol as a basic chiral unit. The details of the synthetic procedures of each requisite chiral binaphthyl subunit have been disclosed, and the structures of the assembled N-spiro chiral quaternary ammonium bromides 11a and 11f were unequivocally determined by single-crystal X-ray diffraction analysis. The reactivity and selectivity of these chiral ammonium bromides as chiral phase-transfer catalysts have been evaluated in the asymmetric alkylation of the benzophenone Schiff base of glycine ester 7 under mild liquid−liquid phase-transfer conditions, and the optimization of the reaction variables (solvent, base, and temperature) has also been conducted. Further, the scope and limitations of this asymmetric alkylation have been thoroughly investigated with a variety of alkyl halides, in...

Design of N-Spiro C2-Symmetric Chiral Quaternary Ammonium Bromides as Novel Chiral Phase-Transfer Catalysts: Synthesis and Application to Practical Asymmetric Synthesis of α-Amino Acids

Orally-active angiotensin-converting enzyme inhibitors are rapidly establishing themselves in the therapy of hypertension and congestive heart failure. Concerted efforts in a number of laboratories have now led to the discovery or synthesis of an unparalleled variety of potent inhibitors. The manner in which several of these inhibitors bind to ACE is beginning to be understood. It is hoped that some of the insights to be derived from the SAR and structural studies done with ACE inhibitors will be applicable to other enzyme targets as well. The success of ACE inhibitors as pharmacological tools and in the clinic will also quite certainly encourage future efforts to develop new enzyme inhibitor approaches to drug therapy.

Charles F. Huebner

Papers

4-(beta-substituted aminoethyl)-imidazoles and the preparation thereof

1 (3)-alkoxyphenyl-3 (1)-alkylphenyl-2-thioureas

Iodinated mercapto-imidazoles

Esters of the yohimbe alkaloids

Di-(p-n-butyl phenyl)-thiourea