Room Temperature Organic Synthesis (eBook)

Goutam Brahmachari (Autor)

eBook Download: PDF | EPUB

2015 | 1. Auflage
386 Seiten
Elsevier Science (Verlag)
978-0-12-801138-6 (ISBN)

Infos

Filling a gap in the scientific literature, Room Temperature Organic Synthesis is unique in its authoritative, thorough, and applied coverage of a wide variety of 'green' organic synthetic methodologies. The book describes practical, feasible protocols for room temperature reactions to produce carbon-carbon and carbon-heteroatom bond formations including aliphatic, aromatic, alicyclic, heterocycles, and more. Consistently organized for easy access, each selected reaction is discussed in a very compact and structured manner including: reaction type, reaction condition, reaction strategy, catalyst, keywords, general reaction scheme, mechanism (in selected cases), representative entries, experimental procedure, characterization data of representative entries, and references. This book will be a valuable resource for synthetic organic, natural products, medicinal, and biochemists as well as those working in the pharmaceutical and agrochemical industry. - Includes more than 300 protocols for a green approach to organic synthesis - Provides specific detail about experimental conditions - Increases efficiency in the laboratory by eliminating time-consuming literature searches

Born on April 14, 1969 in Barala, a village in the district of Murshidabad (West Bengal, India), Goutam Brahmachari had his early education in his native place. He received his high school degree in scientific studies in 1986 at Barala R. D. Sen High School under the West Bengal Council of Higher Secondary Education (WBCHSE). Then, he moved to Visva-Bharati (a Central University founded by Rabindranath Tagore at Santiniketan, West Bengal, India) to study chemistry at the undergraduate level. After graduating from this university in 1990, he completed his master's in 1992, specializing in organic chemistry. After receiving his Ph.D. 1997 in chemistry from the same university, he joined his alma mater the next year and has been a full professor of chemistry since 2011. The research interests of Prof. Brahmachari's group include synthetic organic chemistry, green chemistry, natural products chemistry, and the medicinal chemistry of natural and natural product-inspired synthetic molecules. With more than 25 years of experience in teaching and research, he has produced over 260 scientific publications, including original research papers, review articles, books, and invited book chapters in the field of natural products and green chemistry. He has already authored/edited 27 books published by internationally reputed major publishing houses, namely, Elsevier Science (The Netherlands), Academic Press (Oxford), Wiley-VCH (Germany), Alpha Science International (Oxford), De Gruyter (Germany), World Scientific (Singapore), CRC Press (Taylor & Francis Group, USA), Royal Society of Chemistry (Cambridge), etc. Prof. Brahmachari serves several scientific bodies in India and abroad, and also many international journals as an editorial member. He has also been serving as co-editor-in-chief for Current Green Chemistry. Prof. Brahmachari is the founder series editor of the Elsevier Book Series 'Natural Product Drug Discovery'. Prof. Brahmachari is an elected fellow of the Royal Society of Chemistry and a recipient of the CRSI (Chemical Research Society of India) Bronze Medal-2021 (for his contribution to research in chemistry), Dr Basudev Banerjee Memorial Award-2021 (for his contribution to the field of chemical sciences) from the Indian Chemical Society, INSA (Indian National Science Academy) Teachers Award-2019, Dr Kalam Best Teaching Faculty Award-2017, and Academic Brilliance Award, 2015 (Excellence in Research). Prof. Brahmachari was featured in the World Ranking of the Top 2% Scientists (Organic Chemistry Category) in 2020-23, the AD Scientific World Ranking of Scientists in 2022-2024, and as the Scholar GPS Highly Ranked Scholar-2024 (Lifetime, securing a position in the top 0.05% of all scholars worldwide).

---

Filling a gap in the scientific literature, Room Temperature Organic Synthesis is unique in its authoritative, thorough, and applied coverage of a wide variety of "e;green"e; organic synthetic methodologies. The book describes practical, feasible protocols for room temperature reactions to produce carbon-carbon and carbon-heteroatom bond formations including aliphatic, aromatic, alicyclic, heterocycles, and more. Consistently organized for easy access, each selected reaction is discussed in a very compact and structured manner including: reaction type, reaction condition, reaction strategy, catalyst, keywords, general reaction scheme, mechanism (in selected cases), representative entries, experimental procedure, characterization data of representative entries, and references. This book will be a valuable resource for synthetic organic, natural products, medicinal, and biochemists as well as those working in the pharmaceutical and agrochemical industry. - Includes more than 300 protocols for a green approach to organic synthesis- Provides specific detail about experimental conditions- Increases efficiency in the laboratory by eliminating time-consuming literature searches

Textauszug

Chapter 1

Carbon – Carbon Bond Forming Reactions at Room Temperature

C-C bond_1

Type of reaction: C-C bond formation

Reaction conditions: Solvent-free, room temperature

Synthetic strategy: One-step condensation

Catalyst: Niobium pentachloride (NbCl5)

Keywords: 1,4-Dicarbonyls, aldehydes, niobium pentachloride (NbCl5), homogeneous catalysis, solvent-free, room temperature, condensation, Knoevenagel reaction, trisubstituted alkenes

General reaction scheme

Representative entries

Experimental procedure

A round-bottomed flask was charged with a magnetic stir bar, 1,3-carbonyl compound (1; 1 mmol), and aldehyde (2; 1.2 mmol), followed by 20 mol% of NbCl5. The reaction mixture was then stirred at room temperature for required time-frame (0.75-4.0 h). After completion of the reaction, it was quenched by the addition of saturated aqueous NaHCO3 solution and the product (3) was extracted with ethyl acetate. The product was purified by column chromatography using ethyl acetate/hexane as eluent. Structure of each of the products was verified from IR, 1H NMR, 13C NMR and HRMS studies.

Characterization data of two representative compounds

(E)-Methyl 2-(4-chlorobenzylidene)-3-oxobutanoate (3a): Reddish solid; mp 80 °C; IR (KBr): 821, 1088, 1250, 1618, 1654, 1733, 2362, 2855, 2932 cm− 1; 1H NMR (300 MHz, CDCl3): δ 1.16 (s, 3H), 2.58 (s, 3H), 6.11–6.12 (m, 4H), 6.27 (s, 1H); 13C NMR (75 MHz, CDCl3): δ 26.5, 52.6, 129.1, 130.6, 136.8, 134.5, 140.0, 169.7, 194.3; ESIMS: m/z 261 (M+ + Na); HRMS: Calcd for C12H11O3NaCl, 261.0294; Found 261.0289.

3-(4-Methoxybenzylidene)pentane-2,4-dione (3c): Yellow liquid; IR (neat): 831, 1108, 1174, 1258, 1258, 1513, 1599, 1653, 1706, 2844, 2926, 3004 cm− 1; 1H NMR (300 MHz, CDCl3): δ 2.28 (s, 3H), 2.26 (s, 3H), 3.83 (s, 3H), 6.87 (d, J = 9.0 Hz, 2H), 7.31 (d, J = 9.0 Hz, 2H), 7.37 (s, 1H); 13C NMR (75 MHz, CDCl3): δ 26.2, 31.6, 55.3, 114.5, 125.2, 131.6, 139.7, 140.6, 161.6, 196.4, 206.1; ESIMS: m/z 241 (M+ + Na); HRMS: Calcd for C13H14O3Na, 241.0840; Found 241.0833.

Reference

Yadav JS, Bhunia DC, Singh VK, Srihari P. Solvent-free NbCl5 catalyzed condensation of 1,3-dicarbonyl compounds and aldehydes: A facile synthesis of trisubstituted alkenes. Tetrahedron Lett. 2009;50:2470–2473.

C-C bond_2

Type of reaction: C-C bond formation

Reaction conditions: Water, neutral conditions, room temperature

Synthetic strategy: One-step condensation

[Cage 1: adapted from Murase et al. (2012), J. Am. Chem. Soc., 134, 162]

Catalyst: Heterogeneous, a cationic coordination cage (1) (12 + charged M6L4 cage) [Cage components: (ethylene diamine)Pd(NO3)2 and 2,4,6-tripyridyl-1,3,5-triazine]

Keywords: Aromatic aldehydes, Meldrum’s acid, 12 + charged cage 1 (catalyst), water, room temperature, condensation, Knoevenagel reaction, trisubstituted alkenes

General reaction scheme

Representative entries

Experimental procedure

Aldehyde (2; 0.5 mmol) and Meldrum’s acid (3; 0.5 mmol) were added to an aqueous solution (5 mL) of cage (1; 15.0 mg, 5.00 × 10−3 mmol; 1 mol%), and the reaction mixture was stirred at room temperature for stipulated time (6-96 h). The product was extracted with CHCl3 (2 × 5 mL), and the organic layer was evaporated in vacuo to furnish the condensation product 4 (38-96% yield). The obtained product 4 was purified by recrystallization from refluxing ethanol. Each of the products was fully characterized from its detailed spectral studies including IR, 1H NMR, 13C NMR, MS, and also from analytical analyses.

Cage 1 – a synthetic mimic of enzymes: This technique demonstrated a unique dehydration condensation under neutral conditions in water catalyzed by the water-soluble synthetic cationic host 1. An aromatic aldehyde substrate (2; an electron-rich guest) first became efficiently encapsulated into the host’s (1) hydrophobic cavity, which after then attacked by the enolate of Meldrum’s acid (3) to generate oxyanion intermediate. The condensation reaction seems to be facilitated by the anionic intermediate in the cationic environment of the cage. The eventual loss of water molecule occurs smoothly within the hydrophobic cavity to form the dehydrated product (4) which is too large for the cavity and is spontaneously released from the cage, and a new incoming substrate molecule (2) occupies the position. The overall phenomenon follows the tricks of enzyme-like catalysis.

Characterization data of two representative compounds

5-((6-Methoxynaphthalen-2-yl)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4c): Solid, mp 191.2-192.2 °C; IR (ATR): 2992, 2946, 1756, 1725, 1587, 1402, 1341, 1291, 1222, 1158, 1023, 1010 cm−1; 1H NMR (500 MHz, CDCl3): δ 8.56 (br s,1H), 8.55 (br s,1H), 8.18 (dd, J = 8.8, 1.7 Hz, 1H), 7.85 (d, J = 9.0 Hz, 1H), 7.76 (d, J = 8.8 Hz, 1H), 7.21 (dd, J = 9.0, 2.4 Hz, 1H,), 7.16 (d, J = 2.4 Hz, 1H), 3.97 (s, 3H), 1.83 (s, 6H); 13C NMR (125 MHz, CDCl3): δ 163.8 (C), 160.9 (C), 160.3 (C), 158.5 (CH), 137.8 (C), 137.7 (CH), 131.7 (CH), 129.4 (CH), 128.1 (C), 127.3 (C), 127.1 (CH), 120.0 (CH), 112.7 (C), 106.0 (CH), 104.4 (C), 55.6 (CH3), 27.6 (CH3); GC-MS (EI): m/z = 312 [M]+. Anal. Calcd. for C18H16O5: C, 69.22; H, 5.16. Found: C, 69.11; H, 5.32.

5-(Anthracen-9-ylmethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4d): Solid, mp 193.6-194.3 °C; IR (ATR): 3049, 3031, 3013, 2925, 2854, 1764, 1737, 1631, 1446, 1396, 1385, 1365, 1334, 1292, 1218, 1202, 1123, 1067, 1028; 1H NMR (500 MHz, CDCl3): δ 9.47 (s, 1H), 8.55 (s, 1H), 8.06 (d, J = 8.8 Hz, 2H), 7.84 (d, J = 9.1 Hz, 2H), 7.52 (t, J = 9.1 Hz, 1H), 7.50 (t, J = 8.8 Hz, 1H), 1.90 (s, 6H); 13C NMR (125 MHz, CDCl3): δ 161.91 (C), 157.89 (C), 157.75 (CH), 130.94 (C), 130.29 (CH), 129.34 (CH), 128.63 (C), 127.09 (CH), 126.80 (C), 125.58 (CH), 124.52 (CH), 121.02 (C), 104.97 (C), 28.17 (CH3); GC-MS (EI): m/z = 332 [M]+. Anal. Calcd. for C21H16O4: C, 75.89; H, 4.85; Found: C, 75.66; H, 5.03.

Reference

Murase T, Nishijima Y, Fujita M. Cage-catalyzed knoevenagel condensation under neutral conditions in water. J. Am. Chem. Soc. 2012;134:162–164.

C-C bond_3

Type of reaction: C-C bond formation

Reaction conditions: Ethanol / dichloromethane, room temperature

Synthetic strategy: E or Z-Selective Knoevenagel condensation

Catalyst: Piperidine

Keywords: Aldehydes, O-acetoacetylTEMPO (2,2,6,6-tetramethylpiperidin-1-yl 3-oxobutanoate), N-methoxy-N-methyl-3-oxobutanamide, piperidine, ethanol, room temperature, E- and Z-selective Knoevenagel condensation, trisubstituted E or Z-2-alkenes

General reaction scheme

Representative entries

Experimental procedure

A typical procedure for Knoevenagel condensaton of O-acetoacetylTEMPO (1). To a cooled (0-4 °C) mixture of O-acetoacetylTEMPO (1; 243 mg, 1.0 mmol), 2-furaldehyde (2; 192 mg, 2.0 mmol), and ethanol (4 drops, 20 mg) was added piperidine (two drops, 10 mg). The mixture was allowed to warm gradually to room temperature and was stirred for 2 days. The reaction was quenched with cold aqueous ammonium chloride, and the products were extracted with ethyl acetate. The extracts were washed with brine, dried (MgSO4), and...

Produkt-Details

• Erscheint lt. Verlag: 19.3.2015
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie ► Organische Chemie
• Themenwelt: Technik
• ISBN-10: 0-12-801138-6 / 0128011386
• ISBN-13: 978-0-12-801138-6 / 9780128011386