ChemInform Abstract: Synthesis of Homochiral N‐Boc‐β‐Aminoaldehydes from N‐Boc‐β‐aminonitriles.

Abstract

Synthesis of Homochiral N-Boc-β-Aminoaldehydes from N-Boc-βaminonitriles.-Enantiopure N-Boc-β-aminoaldehydes (II) are efficiently prepared in good yields by partial reduction of the nitrile function in optically pure N-Boc-β-aminonitriles (I) with diisobutylaluminum hydride. -(TOU-JAS, J.-L.; JOST, E.; VAULTIER, M.; Bull.

Stereoselective Total Synthesis of Tubulysin V

“…The chiral amino group in compound 13 was introduced using aqueous aza-Barbier reaction previously developed in our group. [10] Removal of N-tert-butyl sulfinamide in 13 and subsequent protection with Boc 2 O gave the homoallylic amine 19 in 80% yield. The newly formed chiral center was assigned as R configuration according to our previous report, [5b] as well as the comparison of optical rotation with the known compound 10.…”

l-Proline derived nitrogenous steroidal systems: an asymmetric approach to 14-azasteroids

“…PAPER intermediate 2, which in turn could be obtained by coupling of bromo derivative 3 with L-proline derived aldehyde 4. The bromo derivatives 3a-e 15 were obtained by the reaction of substituted/unsubstituted 1-tetralone/chromanone with PBr 3 in dry benzene (Scheme 2), whereas the optically pure aldehyde 4a 16 was synthesized from commercially available N-(Boc)-S-proline by carboxyl reduction, 17a Swern oxidation, 17b Wittig olefination, 17c and enol ether hydrolysis with 2 M HCl (Scheme 2).…”

“…As described for 1a/1a9, 2d/2d9 (80 mg, 0.17 mmol) in dioxane (2 mL), 4 M HCl in dioxane (1.2 mL), Et 3 N (0.12 mL, 0.83 mmol) in MeOH (2 mL) furnished 1d and 1d9 (43 mg, 71%) as viscous colorless oil, For 1d; 17.1), 4.30-4.25 (m, 1H), 3.90-3.83 (m, 1H), 3.80 (s, 3H), 3.04- 9, 138.2, 135.4, 134.2, 129.9, 128.4 (2C), 127.9, 127.7, 127.6 (2C), 118.4, 113.7, 108.3, 76.9, 71.2, 62.9, 59.6, 57.7, 55.3, 38.6, 32.4, 29.3, 27.8 4aS,12aR)-2-(benzyloxy)-9-methoxy-1,2,3,4a,5,6,12,12aoctahydrobenzo[f]pyrrolo[1,2-a]quinoline (1d9) [a] 28 D = +2.83 (c 0.20, CHCl 3 ); R f 0.50 (10% MeOH in CHCl 3 ); IR ( Neat): 2925, 2356, 1634, 1223, 771, cm 21 ; 1 H NMR (300 MHz, CDCl 3 ): d 7.35-7.30 (m, 5H), 6.70-6.94 (m, 2H), 6.73 (dd, 1H, J 1 = 2.7, J 2 = 8.4), 6.13-6. 16 9, 138.1, 137.2, 136.6, 129.6, 128.4(2C), 127.7(2C), 127,6, 127.2, 118.9, 113.8, 108.3, 77.2, 71.4, 56.3, 55.5, 55.3, 52.1, 37.7, 31.9, 29.3, 28.0 3,4a,5,6,12,12aoctahydrobenzo[f]pyrrolo [1,2-a]quinoline (1g)…”

Facile cleavage of C–C bond: conversion of pyrane derivative to 1,3-oxazin derivative

“…Various 1,3-oxazine derivatives have shown a wide variety of bioactivities, such as anti-human coronavirus activity, 7 inhibition of cholesterol esterase and acetylcholinesterase, 8 inhibition of human leukocyte elastase, 9 and nonsteroidal progesterone receptor antagonists. 12 There are several synthetic methods for preparation of 1,3-oxazine derivatives, such as the [4þ2] cycloaddition of an alkene and an N-acylimine, 13 intramolecular hydroamination of trichloroacetimidate, 14 cycloaddition reactions of 2-azadienes with alkenes, 15 Ritter reaction of a diol with a nitrile, 16 intramolecular cyclization of N-thioacyl 1,3-amino alcohols with Bu 4 NF and EtI. 11 These biological activities have prompted synthetic chemists to establish novel 1,3-oxazine ring formation methods to find promising bioactive oxazine compounds.…”