Regioselective and Transition-Metal-Free Addition of tert-Butyl Magnesium Reagents to Pyridine Derivatives: A Convenient Method for the Synthesis of 3-Substituted 4-tert-Butylpyridine Derivatives

Synthesis ◽  
2017 ◽  
Vol 49 (17) ◽  
pp. 4055-4064 ◽  
Author(s):  
Sebastian Rappenglück ◽  
Karin Niessen ◽  
Thomas Seeger ◽  
Franz Worek ◽  
Horst Thiermann ◽  
...  
Keyword(s):  
Transition Metal ◽  
Convenient Method ◽  
Pyridine Derivatives ◽  
Reaction Sequence ◽  
Metal Free ◽  
Tert Butyl ◽  
Microwave Assisted ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Regioselective Addition

A variety of 3,4-disubstituted pyridine derivatives with a tert-butyl group in the 4-position were synthesized in a transition-metal-free, two-step reaction sequence from 3-substituted pyridine precursors. Highly regioselective addition of t-Bu2Mg to TIPS-activated pyridines and an efficient microwave-assisted aromatization with sulfur as oxidant afforded the desired 3,4-disubstituted pyridine derivatives in moderate to excellent yields. The method is compatible with many functional groups such as ester, amide, halide, nitrile or alkyne groups present in the 3-position.

Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

Reactions of benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite: "balanced TS" validating reactivity/selectivity principle

1998 ◽  
Vol 76 (6) ◽  
pp. 836-842
Author(s):  
Sung Soo Kim ◽  
Yu Zhu ◽  
In Seok Oh ◽  
Chang Gyeong Lim
Keyword(s):  
Benzyl Chloride ◽  
Activation Parameters ◽  
Differential Activation ◽  
Tert Butyl ◽  
Benzyl Chlorides ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Polar Transition ◽  
Isokinetic Relations ◽  
Selectivity Principle

Reactions of a series of several benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite were investigated. The reactions produced phosphates, isobutene, alkyl chlorides, and benzyl chlorides via phosphonium chlorides as intermediates. Furthermore, the phosphates bearing a tert-butyl group underwent fragmentation to yield isobutene and another phosphates. Relative rates of formations of substituted benzyl and benzyl chloride (kY/kH) were measured at the temperatures (-20, 0, 20, 40°C). Logarithms of the rates (log kY/kH) were plotted against sigma + and 1/T, respectively. The former gave Hammett correlations to suggest a polar transition state (TS). The latter yielded differential activation parameters (ΔΔ Hdouble daggerY-H and ΔΔ Sdouble daggerY-H ), which indicate isokinetic relations and enthalpy control of rates. The selectivities (kY/kH) decrease with higher temperatures and thereby follow the reactivity/selectivity principle.Key words: phosphites, tert-butyl hypochlorite, Hammett correlations, differential activation terms, reactivity/selectivity principle.

Evaluation of the tert-butyl group as a probe for NMR studies of macromolecular complexes

2021 ◽  
Author(s):  
Rashmi Voleti ◽  
Sofia Bali ◽  
Jaime Guerrero ◽  
Jared Smothers ◽  
Charis Springhower ◽  
...  
Keyword(s):  
Nmr Studies ◽  
Macromolecular Complexes ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Michael addition of amines to sterically crowded ortho-benzoquinone completed with unprecedented 1,2-shift of a tert-butyl group

Tetrahedron ◽  
2021 ◽  
Vol 79 ◽  
pp. 131841
Author(s):  
Eugeny Ivakhnenko ◽  
Vasily Malay ◽  
Galina Romanenko ◽  
Oleg Demidov ◽  
Pavel Knyazev ◽  
...  
Keyword(s):  
Michael Addition ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Tri(Terf-Butyl)plumbyl-phosphanes, Synthesis and Multinuclear Magnetic Resonance

2000 ◽  
Vol 55 (10) ◽  
pp. 939-945 ◽  
Author(s):  
Max Herberhold ◽  
Christian Köhler ◽  
Volker Tröbs ◽  
Bernd Wrackmeyer
Keyword(s):  
Magnetic Resonance ◽  
Phosphorus Atom ◽  
Coupling Constants ◽  
Tert Butyl ◽  
Nmr Data ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Multinuclear Magnetic Resonance

AbstractThe reaction of tri(tert-butyl)plumbyl-lithium (1) with various phosphorus chlorides was studied. With diphenyl- and amino(phenyl)phosphorus chlorides the formation of hexa(tertbutyl) diplumbane (2) and tetraphenyldiphosphane (3) or the respective 1,2-bis(am ino)-1,2-diphenyl- diphosphanes [e. g. 5: amino = PhCH2(tBu)N] was dominant. The presence of at least one tert-butyl group at the phosphorus atom gave access to tri(tert-butyl)plumbyl-di(tert-butyl) phosphane (4) and to tri(tert-butyl)plumbyl-amino(tert-butyl)phosphanes [amino = tBu(H)N (6), Me(Ph)N (7), PhCH2(Me)N (8), PhCH2(tBu)N (9)] via the reaction of 1 with the corresponding phosphorus chlorides. Side products were again 2 and the corresponding diphosphanes, unidentified compounds, and in two cases, bis(phosphanyl)-di(tert-butyl)plumbanes [phosphanyl = tBu(H)N(tBu)P (10), Me(Ph)N(tBu)P (11)]. Trimethylplumbyl-benzyl(methyl)- amino(tert-butyl)phosphane (12) was prepared for comparison. All compounds were characterized by their 1H , 13C, 15N (9 ),31P and 207Pb NMR data. The coupling constants 1J(207Pb,31P) are large and negative, whereas the coupling constants 1J(207Pb, 13C) are small and can be of either sign. The coupling constants 2J(31P-N-13C) of 6 - 12 indicate a preferred conformation of the substituents at phosphorus and nitrogen

ChemInform Abstract: A CASE OF A FACILE CLEAVAGE OF AN ANGULAR TERT-BUTYL GROUP

1981 ◽  
Vol 12 (28) ◽  
Author(s):  
V. A. KAMINSKII ◽  
T. V. ZABOLOTNOVA ◽  
T. V. NOVIKOVA ◽  
T. M. TILICHENKO
Keyword(s):  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Iodine mediated oxidative cross coupling of 2-aminopyridine and aromatic terminal alkyne: a practical route to imidazo[1,2-a]pyridine derivatives

2019 ◽  
Vol 17 (26) ◽  
pp. 6441-6449 ◽  
Author(s):  
Surya Kanta Samanta ◽  
Mrinal K. Bera
Keyword(s):  
Transition Metal ◽  
Oxidative Coupling ◽  
Cross Coupling ◽  
Terminal Alkyne ◽  
Pyridine Derivatives ◽  
Metal Free

A novel, transition-metal free route leading to imidazo[1,2-a]pyridine derivatives via iodine mediated oxidative coupling between 2-aminopyridine and aromatic terminal alkyne has been demonstrated.

Visible-light-induced tandem cyclization of 2-alkynylanilines with disulfides: a convenient method for accessing benzothiophenes under transition-metal-free and photocatalyst-free conditions

2017 ◽  
Vol 15 (36) ◽  
pp. 7678-7684 ◽  
Author(s):  
Xiaoyu Xie ◽  
Pinhua Li ◽  
Qing Shi ◽  
Lei Wang
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Convenient Method ◽  
Metal Free ◽  
Efficient Route ◽  
Tandem Cyclization

An efficient route to benzothiophenes via visible-light induced cyclization of 2-alkynylanilines with disulfides under transition-metal-free and photocatalyst-free conditions was developed.

The tert-butyl group in chemistry and biology

2008 ◽  
Vol 6 (15) ◽  
pp. 2655 ◽  
Author(s):  
Philippe Bisel ◽  
Loay Al-Momani ◽  
Michael Müller
Keyword(s):  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Synthesis of 1-tert-Butyl-4-chloropiperidine:  Generation of anN-tert-Butyl Group by the Reaction of a Dimethyliminium Salt with Methylmagnesium Chloride

2005 ◽  
Vol 70 (5) ◽  
pp. 1930-1933 ◽  
Author(s):  
Joseph S. Amato ◽  
John Y. L. Chung ◽  
Raymond J. Cvetovich ◽  
Xiaoyi Gong ◽  
Mark McLaughlin ◽  
...  
Keyword(s):  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group
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