Katritzky Advances in Heterocyclic Chemistry

1. Auflage 2015
ISBN: 978-0-12-800399-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, Band Volume 112, 244 Seiten

Reihe: Advances in Heterocyclic Chemistry

Established in 1960, Advances in Heterocyclic Chemistry is the definitive serial in the area-one of great importance to organic chemists, polymer chemists and many biological scientists. Written by established authorities in the field, the comprehensive reviews combine descriptive chemistry and mechanistic insight and yield an understanding of how the chemistry drives the properties. - One of great importance to organic chemists, polymer chemists and many biological scientists - Written by established authorities in the field, the comprehensive reviews combine descriptive chemistry and mechanistic insight and yield an understanding of how the chemistry drives the properties

Autoren/Hrsg.

Katritzky, Alan R.

Leseproben

Chapter One Pechmann Reaction in the Synthesis of Coumarin Derivatives
Majid M. Heravi1, Soheila Khaghaninejad and Manizhe Mostofi     Department of Chemistry, School of Sciences, Alzahra University, Vanak, Tehran, Iran
1 Corresponding author: E-mail: [e-mail] 
Abstract
The Pechmann reaction introduces one of the most significant and simple methods for the synthesis of a variety of heterocyclic compounds, particularly coumarin derivatives. In 1883, a German chemist, Hans von Pechmann synthesized coumarins from the reaction of phenols with a carboxylic acid or ester containing a ?-carbonyl group. In this article, we try to highlight the various aspects, issues, and applications of this reaction. Keywords
Catalyst; Catalytic reaction; Coumarin; Pechmann 1. Introduction
Coumarins are extensively found in the field of biology, medicine, and polymer sciences. The most well-known and important coumarin is “warfarin”, which is prescribed in low doses as a blood thinner. Numerous coumarins are used as a drug in contemporary and recent medicine. Among them warfarin 1, acenocoumarol 2, and phenprocoumon 3 are vitamin K antagonists, which play anticoagulant starring role in treatment of thromboembolic syndromes (Figure 1) (08MI1052).
Figure 1 Warfarin 1, acenocoumarol 2, and phenprocoumon 3.
Figure 2 (+)-Cordatolide A 4, (+)-inophyllum B 5, (+)-calanolide A 6, ayapin 7, and carbochromen 8. The organic and medicinal chemists have synthesized a large number of bioactive natural products that contain coumarin heterocyclic nucleus such as (+)-cordatolide A 4, (+)-inophyllum B 5, (+)-calanolide A 6, ayapin 7, and carbochromen 8 (Figure 2) (08SC4395). Some polycyclic coumarins like calanolides (92JMC2735) have been isolated from calophyllum genus (12MI1a). Coumarin and its derivatives also exhibit other wide range of various physiological activities, including anti-inflammatory (04MI3813), antibacterial (05MI693), anticancer (05MI29, 02MI163), anticlotting (06MI764), anti-HIV activities (02FA703), antiviral (00BMC59), antioxidant (87P2489, 81MI240), as well as platelet aggregation (98JIC666, 01TA707), insecticides (97MI1), and inhibition of steroid 5?-reductase (12MI1a, 01BMC2361). They are also used as ingredients in perfumes, cosmetics, additives in food, pharmaceuticals (97MI1), in the preparation of insecticides, optical brighteners (01TL9285, 02TL9195, 92MI1), and dispersed fluorescent and laser dyes (82MI1). Coumarins have been taken into consideration because of their toxicity (72JOC3368) and carcinogenity (74JMC109). Furthermore, they show photodynamic effects (75JA154) and are useful intermediates for the synthesis of furocoumarins, chromenes, coumarones, and 2-acylresorcinols (45CRV1).
Scheme 1  In 1883, a German chemist, Hans von Pechmann (Nurnberg 1 April 1850-Tubingen 19 April 1902), discovered a novel condensation leading to coumarins and reported this important and resourceful reaction in Berichte der deutschen chemischen Gesellschaft (1883MI2119, 1884CB929). It is worthwhile to mention that Pechmann also reported the synthesis of pyrazoles (1898MI2950) from the reaction of acetylene with diazomethane (1894MI1888, 1895MI855). The synthesis and characterization of diazomethane as a very useful and multipurpose basic chemical was much distinguished and celebrated at that time and his fame spread across the world of chemistry. Back to our tenacity and purpose, he reported the synthesis of coumarins from the reaction of phenols with a carboxylic acid or ester containing a ?-carbonyl group (Scheme 1). This method has opened a very precious and useful gateway to the preparation of a series of an important oxygen-containing heterocyclic compounds, namely, coumarin and its derivatives. In this article, we try to highlight the various aspects, issues, and applications of this reaction with the hope of winning the attentions and considerations of synthetic organic chemists. 2. Mechanism
The Pechmann reaction is commonly performed under acidic conditions. The mechanism involves an esterification/transesterification followed by attack of the activated carbonyl ortho to the oxygen to create a new ring. The final step is dehydration, followed by an aldol condensation. It is performed by catalytic activity of (1) strong Brønsted acids or (2) Lewis acids.
Scheme 2 
Scheme 3 
Scheme 4  1. Via a strong Brønsted acid such as sulfuric acid (Scheme 2) or methanesulfonic acid (55MI136, 94S87, 05MI117). 2. Via a Lewis acid such as AlCl3 (Scheme 3) and in general (Scheme 4). The synthesis of coumarin with simple phenols under the Pechmann conditions are problematic and harsh reaction conditions are required to move the reaction forward, although the yields may still be reasonable (55OS581). On the contrary, the reaction with highly activated phenols such as resorcinol can be carried out under much milder conditions. This provides a useful route to 7-hydroxychromen-2-one (umbelliferone) 9 from the in situ reaction of the formylacetic acid, generated from malic acid, with resorcinol (Figure 3) (Scheme 2).
Figure 3 7-Hydroxychromen-2-one (umbelliferone) 9. 3. Synthesis of Coumarins via Pechmann Reaction
Coumarins can be synthesized by several routes including von Pechmann (1884CB929), Perkin (42OR210, 1875JCS10), Knoevenagel (67OR204, 96H1257), Reformatsky (42OR1), Wittig (90SC1781, 34OS270, 79S906) and Claisen rearrangement (94JCS(P1)3101), catalytic cyclization reactions (98JCR(S)800), and by flash vacuum pyrolysis (97JCR(S)296). However, this chapter focuses on the applications of Pechmann and Pechmann type reactions in the synthesis of various coumarin derivatives. 3.1. Variety of Catalysts
Several acid catalysts have been used in the von Pechmann reaction including H2SO4 (1884CB929), montmorillonite/clay (01TL2791), [bmim]Cl·2AlCl3 (01TL9285), [bmim]HSO4 (05CCAOAC57), InCl3 (02TL9195), P2O5 (14CB2229, 31JCS2426), BiCl3 (06SC525), GaI3 (05SC1875), Zeolite (06MI105), Zeolyst (mordenite)/U.S. (09MI318), ZrOCl2·8H2O/SiO2 (11CCAOAC62), HClO4 (96DP99), HClO4·SiO2 (06JMCCF249), sulfated zirconia (06TL3279), Keggin heteropolyacids (HPAs) (08MI53), Wells–Dawson HPA (H6P2W18O62·24H2O, 04TL8935), H14[NaP5W30O110] (07CCAOAC1886), phosphotungstic acid (H3PW12O40) (09MI321), SnCl2·2H2O, sulfonic acid nanoreactors, HCl, CF3COOH (62JOC3703), and so forth (31JCS2426, 35JCS1031, 62JOC3703, 97JCR(S)58), Aluminium chloride (AlCl3) (38JCS228), anhydrous Iron(III) chloride (FeCl3) (08SC2646), Ytterbium(III) trifluoromethanesulfonate hydrate (Yb(OTf)3) (03IJC2079, 62JOC3703), Zinc chloride (ZnCl2) (90JCS(P1)2151), Zinc chloride/Aluminium oxide (ZnCl2/Al2O3) (03MI143), Zirconium(IV) chloride (ZrCl4) (04SC3997), Samarium nitrate (Sm(NO3)3) (04TL7999), Phosphoryl chloride (POCl3) (87JIC254, 37PIA277), Phenylpropanolamine (PPA) (81IJC719), p-Toluenesulfonic acid (PTSA) (01CL110), Phosphoric acid (H3PO4), dipyridine copper chloride (CuPy2Cl2), pentafluorophenylammonium triflate (PFPAT) (11JFC450), ceric ammonium nitrate (CAN) (08SC2082), Barium chloride (BaCl2) (12MI1a), Boron Trifluoride Dihydrate (BF3·2H2O) (05MI762), Titanium tetrachloride (TiCl4) (05TL3501), Copper perchlorate (Cu(ClO4)2)/U.S. (09MI705), solid acid W/ZrO2 (01SC3603, 05JMCCF271), Nafion resin/silica nanocomposites (03MI315), polyaniline sulfate salts (04JMCCF2117), Amberlyst-S (05MI34), polyaniline-fluoroboric acid-dodecylhydrogensulfate (PANI-HBF4-DHS) salt (05JMCCF29), Silica supported perchloric acid (HClO4·SiO2) (06JMCCF249), SO42?/CexZr1 ? xO2 composite solid acid catalyst (SO42?/CexZr1 ? xO2) (06JMCCF2290), Chlorosulfuric acid (ClSO3H) (06MC241), oxalic acid (07MI1309), silica triflate (07MI909), Benzylsulfonic acid functionalized mesoporous Zr-TMS (Zr-TMS-BSA, Zr-TMS, zirconia based transition metal oxide mesoporous molecular sieves) (Zr-TMS-BSA) (07CCAOAC777), PW (phosphotungstic acid) supported Al-MCM-41 (Si/Al = 25) catalysts (PW/Al-MCM-41) (08JMCCF222), Al-MCM-41 (Mobil Composition Mater) (Si/Al = 25) with different Si/Al ratios (Al-MCM-41) (08JMCCF222), Keggin-type...