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Science of Synthesis Knowledge Updates 2014 Vol. 4
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Veröffentlicht 2015, von Klaus Banert, Dennis Hall, John A. Joule, Mark Moloney, Hans-Ulrich Reißig, Ernst Schaumann bei Thieme
ISBN: 978-3-13-176351-8
Auflage: 1. Auflage
Reihe: Science of Synthesis
520 Seiten
The Science of Synthesis Editorial Board, together with the volume editors and authors, is constantly reviewing the whole field of synthetic organic chemistry as presented in Science of Synthesis and evaluating significant developments in synthetic methodology. Four annual volumes updating content across all categories ensure that you always have access to state-of-the-art synthetic methodology.
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5.2.17.9 Acylstannanes (Including S, Se, and Te Analogues) (Update 2014)
P. B. Wyatt
5.2.17.9.1 Applications of Acylstannanes in Organic Synthesis 5.2.17.9.1.1 Method 1: Synthesis of beta,Gamma-Unsaturated Ketones by Acylation of Allylic Esters with AcylstannanesAcylstannanes 1 react with allyli esters 2 in the presence of palladium(II) trifluoroacetate as catalyst to provide good yields of beta,Gamma-unsaturated ketones 3 (_ Scheme 1).[1] Similar transformations may be achieved using acylsilanes in place of acylstannanes;[2] however, for introduction of the benzoyl group, the tin reagents provide much higher yields than their silicon counterparts, as well as a greatly reduced risk of isomerization to form the _,beta-un-saturated isomers of the ketone products.
Scheme 1 Synthesis of beta,Gamma-Unsaturated Ketones[1]
R1 R2 R3 Temp(°C) Yield(%) Ref Ph Me H rt 76 [1] (CH2)5Me Me H 50 71 [1] Ph Bu H rt 64 [1] Ph Me Ph rt 50 [1] (E)-1,4-Diphenylbut-3-en-1-one (3, R1 = R3 = Ph); Typical Procedure:[1]A mixture of acylstannane 1 (R1 = Ph; R2 = Me; 121 mg, 0.50 mmol; as reported), allylic trifluoroacetate 2 (R3 = Ph; 115 mg, 0.50 mmol), Pd(OCOCF3)2 (8.0 mg, 0.025 mmol), and THF (0.25 mL) was stirred under argon at rt for 8 h. The product 3 was isolated following column chromatography (silica gel, hexane/EtOAc 9:1); yield: 50%.
5.2.17.9.1.2 Method 2: Synthesis of _-Oxoamides by Reaction of Stannanecarboxamides with Acyl ChloridesThe stannanecarboxamide 4 readily couples with acyl chlorides 5 to form _-oxoamides 6 (_ Scheme 2); no catalyst is needed.[3] Use of dichlorides, such as oxalyl chloride, allows polycarbonyl compounds to be prepared.
Scheme 2 Synthesis of _-Oxoamides by Reaction of Stannanecarboxamides with Acyl Chlorides[3]
R1 Temp(°C) Time(h) Yield(%) Ref Me rt 1 83 [3] iPr rt 1 87 [3] (E)-CH=CHPh rt 1 85 [3] Ph rt 3 85 [3] (CF2)2CF3 60 1 76 [3] N,N-Diisopropyl-2-oxopropanamide (6, R1 = Me); Typical Procedure:[3]At rt, to a soln of iPr2NCOSnMe3 (4; 1.1 mmol) and docosane (0.37 mmol, internal standard for GC analysis) in benzene (2 mL) (CAUTION: carcinogen) was added AcCl (1.0 mmol) over 10 min and the soln was stirred at rt for 1 h. Volatiles were evaporated and the residue was subjected to column chromatography (silica gel, hexane then CH2Cl2) to give 2-oxoamide 6 (R1 = Me) as a colorless oil; yield: 83%.
5.2.17.9.1.3 Method 3: Synthesis of 3-(Trialkylstannyl)alk-2-enamides by Carbamoylstannylation of Terminal AlkynesTerminal alkynes 7 undergo carbamoylstannylation upon treatment with the
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