The Dolastatins. 17. Synthesis of Dolaproine and Related Diastereoisomers

New Proline–Oxazoline Ligands and Their Application in the Asymmetric Nozaki–Hiyama–Kishi Reaction

“…Proline was protected as either the N-carbobenzyloxy (Cbz) or tert-butoxycarbonyl (Boc) under standard conditions in excellent yields (86-96 %). [10,11] Anilino-oxazoline 6 was prepared by the reaction of anthranilonitrile (7) with the corresponding chiral amino alcohol in the presence of ZnCl 2 in yields of 65-77 %. [12] This is a shorter and higher Figure 2.…”

“…Two such examples are the total synthesis of palytoxin and halichondrin B, which both involve extensive use of chromium additions. [15] To date there has been a limited range of ligand classes applied to the enantioselective process, with the most promising examples emerging from the groups of Sigman (3), [5] Cozzi and Umani-Ronchi (11), [16] Nakada (12, 13), [17] Berkessel (14), [18] Kishi (15) [19] and ourselves (4) [8,9] (Figure 5). Our new ligand class 5 was applied in the chromiumcatalysed reaction of allyl bromide with benzaldehyde (Table 1).…”

Studies on stereoselective approaches to β-carboline derivatives

“…Optical rotations were measured with a Perkin-Elmer 241 polarimeter. TLC was carried out using Kieselgel [19] were synthesized by literature methods. Details of reacylation experiments were reported previously [9].…”

New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

“…Thus, proline was initially protected to give the Bocderivative 4 [32], which was reacted with 2-aminopyridine using EDC as condensation reagent (EDC = N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride) to provide the amide [33,34], which, after Boc removal in acidic medium [35], afforded 5. Reduction of 5 with LiAlH 4 provided derivative 6 (Scheme 1) [36].…”