N,N′,N″-Tri-Boc-guanidine (TBG): a common starting material for both N-alkyl guanidines and amidinoureas (original) (raw)
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Bioorganic & Medicinal Chemistry Letters, 2008
Transformation of aminoacridines into N-acridinyl-N 0 -alkylguanidines is described. The chosen procedure allows introduction of pendent substituents (exemplified by N,N-dimethylaminopropyl chain) into key acridinyl thioureas, thus opening the way to structural diversity. Spectroscopic study and pK a determination show that the presence of the strongly basic guanidine has a dramatic influence on the ionization of the acridine nucleus by lowering the pk a value down to 4.49.
A novel facile solid-phase strategy for the synthesis of N, N', N?-substituted guanidines
Tetrahedron, 2002
AbstractÐA new facile solid-phase synthesis of N,N 0 ,N 00 -substituted guanidines from an immobilised amine component is described. The resin-bound amine was reacted with di-(2-pyridyl)thionocarbonate to generate the isothiocyanate which was treated with aryl/alkyl amines to yield the corresponding resin-bound thiourea. Desulfurisation of the thiourea was readily achieved by treatment with triphenylphosphine dichloride, and further reaction with aryl/alkyl amines followed by acidic cleavage with tri¯uoroacetic acid yielded N,N 0 ,N 00 -substituted guanidines of excellent purity and in good yield. q
Effect of substitution at N″-position of N′-hydroxy-N-amino guanidines on tumor cell growth
Bioorganic & Medicinal Chemistry Letters, 2012
Structural modification of one of our earlier reported lead molecule (ABNM13) has been carried out to study the effect of different substituents at the N 00 -position of N-hydroxy-N 0 -amino guanidines (HAGs) on their anticancer activity. Compounds with electron donating substituents were found to be less active. In contrast, those with electron withdrawing groups were found favorable for anticancer activity. The obtained results provide significant SAR information that may be useful for further drug designing with HAGs.
Organic Letters, 2004
The following general experimental procedure applies for all experiments described in this paper. Unless otherwise stated, all reactions were performed under nitrogen using flame-dried glassware. Reaction solvents were distilled under an inert atmosphere before use and transferred via syringe using standard techniques unless otherwise stated. THF, diethyl ether, and benzene were distilled from sodiumbenzophenone ketyl under argon. CH 2 Cl 2 and MeCN were distilled from CaH 2 under argon and MeOH and EtOH were dried over 4 Å molecular seizes and stored under nitrogen. All other solvents were used as obtained except hexanes, which was distilled prior to use. All reagents, unless otherwise stated, were used as received (Aldrich, Fisher Scientific Ltd. or Lancaster). Crystalline Pr 4 NIO 4 was conveniently prepared by treatment of equimolar amounts of Pr 4 NOH and HIO 4 in water (Keck, G. E.; Fleming, S. A.
A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis
Beilstein Journal of Organic Chemistry, 2016
Starting from (S)-β-phenylalanine, easily accessible by lipase-catalyzed kinetic resolution, a chiral triamine was assembled by a reductive amination and finally cyclized to form the title compound 10. In the crystals of the guanidinium benzoate salt the six membered rings of 10 adopt conformations close to an envelope with the phenyl substituents in pseudo-axial positions. The unprotonated guanidine 10 catalyzes Diels–Alder reactions of anthrones and maleimides (25–30% ee). It also promotes as a strong Brønsted base the retro-aldol reaction of some cycloadducts with kinetic resolution of the enantiomers. In three cases, the retro-aldol products (48–83% ee) could be recrystallized to high enantiopurity (≥95% ee). The absolute configuration of several compounds is supported by anomalous X-ray diffraction and by chemical correlation.
Synthesis and applications of C2-symmetric guanidine bases
Tetrahedron Letters, 2003
The preparation of the tetracyclic C 2 -symmetric guanidinium salts 5 and 11-13 is reported together with their application to enantioselective transformations. Scheme 1. Reagents and conditions: (a) TBDMSCl/imid (99%); (b) DIBAL-H (95%); (c) TosCl/Py (85%); (d) NaI/acetone (89%); (e) i. CH 3 COCHPPh 3 /nBuLi, ii. aq. CH 2 O (79%); (f) i. guanidine/DMF, ii. HCl/MeOH, iii. NaBF 4 (aq.) (44%).
2019
Toward a method for direct conversion of alkenes to cyclic guanidines, we report that 1,3-dipolar cycloadditions of 2-amido-1,3-diamino allylic cations with electron rich alkenes provides a new method for direct cyclic guanidine annulation. Generated under oxidative conditions, the 2-amido-1,3-diaminoallyl cations, react as 1,3-dipoles providing rapid access to 2-amino imidazolines through net (3+2) cycloadditions. The utility is demonstrated through a concise synthesis of the oroidin alkaloid, phakellin. The described 1,3-dipole also participates in net (4+3) cycloadditions with dienes. Several observations suggest a stepwise, ionic, net cycloaddition leading to initial carbocation formation as evidenced by initial formation of constitutional isomers and intervening eliminations. Complex aziridines are formed with dienes suggestive of nitrene intermediates and results in net tetra-functionalization of dienes.