scholarly journals A direct method for the N-tetraalkylation of azamacrocycles

2016 ◽  
Vol 12 ◽  
pp. 2457-2461 ◽  
Author(s):  
Andrew J Counsell ◽  
Angus T Jones ◽  
Matthew H Todd ◽  
Peter J Rutledge
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Direct Synthesis ◽  
Benzyl Bromide ◽  
Solvent System ◽  
Propargyl Bromide ◽  
Partially Miscible ◽  
Derivatives Of ◽  
A Direct Method ◽  
Organic Solvent System

An efficient protocol for the direct synthesis of N-tetraalkylated derivatives of the azamacrocycles cyclam and cyclen has been developed, using a partially miscible aqueous–organic solvent system with propargyl bromide, benzyl bromide, and related halides. The method works most effectively when the reaction mixture is shaken, not stirred. A crystal structure of the N-tetrapropargyl cyclam derivative 1,4,8,11-tetra(prop-2-yn-1-yl)-1,4,8,11-tetraazacyclotetradecane diperchlorate is reported.

scholarly journals A Simple and Direct Synthesis of 3-Methylene-1, 4-diarylazetidin-2-ones and (E)-3-Arylidene-1-phenylazetidin-2-ones Using Baylis–Hillman Derivatives

2014 ◽  
Vol 67 (2) ◽  
pp. 295 ◽  
Author(s):  
Manickam Bakthadoss ◽  
Jayakumar Srinivasan ◽  
Raman Selvakumar
Keyword(s):  
Direct Method ◽  
Direct Synthesis ◽  
Single Step ◽  
Amino Ester ◽  
Derivatives Of ◽  
A Direct Method

Herein we describe a direct method, promoted by potassium tert-butoxide (KOtBu), for the synthesis of highly substituted α-methylene β-lactams and α-arylidene β-lactams from the amino ester intermediates derived from the acetates and bromo derivatives of the Baylis–Hillman adducts. A variety of β-lactams was synthesized in a single step with good yields.

scholarly journals Crystal structure of a new HfO(OH)2 oxyhydroxide

2013 ◽  
Vol 28 (S2) ◽  
pp. S510-S518
Author(s):  
N.V. Tarakina ◽  
A.P. Tyutyunnik ◽  
Ya.V. Baklanova ◽  
L.G. Maksimova ◽  
T.A. Denisova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Pair Distribution Function ◽  
Direct Method ◽  
X Ray ◽  
Ion Exchange Reaction ◽  
Atomic Pair Distribution Function ◽  
Profile Fitting ◽  
Atomic Pair ◽  
Full Profile ◽  
A Direct Method

The crystal structure of a new hafnium oxyhydroxide obtained by an ion-exchange reaction from a Li2HfO3 precursor has been solved by a direct method and refined using Rietveld full profile fitting based on X-ray powder diffraction data. HfO(ОН)2 crystallizes in a P21/c monoclinic unit cell (a = 5.5578(5) Å, b = 9.0701(10) Å, c = 5.7174(5) Å, β = 119.746(5)°); its structure can be described as a framework formed by edge-sharing HfO6 octahedra connected to each other via vertices. In addition, an analysis of the atomic pair distribution function obtained using synchrotron radiation was used to confirm the model and to describe fine-structure features.

A direct method for the preparation of 2-hydroxyethoxymethyl derivatives of guanine, adenine, and cytosine

1980 ◽  
Vol 23 (5) ◽  
pp. 572-574 ◽  
Author(s):  
Jorge R. Barrio ◽  
Jerry D. Bryant ◽  
Gene E. Keyser
Keyword(s):  
Direct Method ◽  
Derivatives Of ◽  
A Direct Method

Crystal Structure of an Ammonium Dithiocyanatocuprate(I) Complex with 18-Crown-6, [NH4(18-Crown-6){Cu(NCS)2}] Obtained from Zero Valent Metal

1997 ◽  
Vol 52 (11) ◽  
pp. 1311-1314 ◽  
Author(s):  
Julia A. Manskaya ◽  
Volodimir N. Kokozay ◽  
Konstantin V. Domasevitch
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
One Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
A Direct Method

The new macrocyclic dithiocyanatocuprate(I) complex [NH4(18-crown-6){Cu(NCS)2}] has been prepared using a direct method of interaction and characterized by X-ray crystallography (orthorhombic, space group Cmc21, with a = 12.453(2), b = 21.650(4), c = 8.151(2) Å, V = 2197.6(8) Å3, Z = 4 , R1 (F) = 0.054; wR2(F2) = 0.141 for 972 unique reflections with I > 2σ(I) and R1(F) = 0.082; w/?2(F2) = 0.210 for all 1098 unique reflections). The lattice comprises complex cations [NH4(18-crown-6)]+ and infinite polymeric anions [Cu(NCS)2]- of a one-dimensional zig-zag structure. The copper atoms adopt three-fold coordination [CuN2S] (Cu-N 1,89( 1), 1,90( 1) Å; Cu-S 2.278(4) Å).

Crystal structure of KBSi3O8 isostructural with danburite

1993 ◽  
Vol 57 (386) ◽  
pp. 157-164 ◽  
Author(s):  
Mitsuyoshi Kimata
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
3 Dimensional ◽  
Tetrahedral Sites ◽  
Structural Types ◽  
Coupled Substitution ◽  
Insight Into

AbstractThe crystal structure of KBSi3O8 (orthorhombic, Pnam, with a = 8.683(1), b = 9.253(1), c = 8.272(1) Å,, V = 664.4(1) Å3, Z = 4) has been determined by the direct method applied to 3- dimensional rcflection data. The structure of a microcrystal with the dimensions 20 × 29 × 37 μm was refined to an unweightcd residual of R = 0.031 using 386 non-zero structure amplitudes. KBSi3O8 adopts a structure essentially different from recdmergneritc NaBSi3O8, with the low albite (NaAlSi3O8) structure, and isotypic with danburite CaB2Si2Os which has the same topology as paracelsian BaAl2Si2O8. The chenfical relationship between this sample and danburitc gives insight into a new coupled substitution; K+ + Si4+ = Ca2+ + B3+ in the extraframework and tetrahedral sites. The present occupancy refinement revealed partial disordering of B and Si atoms which jointly reside in two kinds of general equivalent points, T(1) and T(2) sites. Thus the expanded crystal-chemical formula can be written in the form K(B0.44Si0.56)2(B0.06Si0.94)2O8The systematic trend among crystalline compounds with the M+T3+T4+3O8 formula suggests that they exist in one of four structural types; the feldspar structures with T3+/T4+ ordered and/or disordered forms, and the paracelsian and the hollandite structures.

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