Dieckmann condensation, synthesis

Dicoumarol — see Coumarin, 3,3 -methylenebis(4-hydroxy-Dictamnine biosynthesis, 4, 992 occurrence, 4, 989 pharmacology, 4, 992 synthesis, 4, 990 Dicyanocobyrinic acid heptamethyl ester, 4, 422 Dicycloalkaselenophenes synthesis, 4, 968 Dicyclohexa-1,4-diselenins thermolysis, 4, 968 Dieckmann condensation chroman-3-one synthesis by, 3, 854 isochroman-4-one synthesis by, 3, 859 oxoindolizidine synthesis by, 4, 471... 

In the course of a synthesis of ( )-nootkatone the keto-ester (148) with ethylidenetriphenylphosphorane gave the cyclohexanone (149), a Dieckmann condensation having occurred under the basic conditions. Among other natural products synthesized using Wittig reagents are... 

Condensations Highly atom economical since small molecules of water or alcohol are liberated Atom economy increases as the molecular weights of the combining fragments increases For cyclization reactions such as the Dieckmann condensation and the synthesis of cyclic ethers from straight chain diols the atom economy increases with increasing ring size... 

The term condensation refers to the joining of two molecules with the splitting out of a smaller molecule. The Claisen condensation is used extensively in the synthesis of dicarbonyl compounds. In biochemistry it is used to build fatty acids in the body. The Dieckmann condensation, the crossed Claisen condensation, and others (with other carbanions) cire variations of the Claisen condensation. In this section we briefly look at these variations. 

Kulkarni, B. A. Ganesan, A. Ion-Exchange Resins for Combinatorial Synthesis 2,4-Pyrrolidinediones by Dieckmann Condensation, Angew Chem. Int. Ed. Engl. 1997, 36, 2454. 

This interesting reaction is especially useful for the synthesis of medium- and large-ring compounds from dicarboxylic esters, and is effective for ring sizes that cannot be made by the Dieckmann condensation or decarboxylation (Section 18-1 OB). Radical anions formed by addition of sodium to the ester... 

The utilization of the Mitsunobu reaction and Dieckmann condensation has been demonstrated for the highly efficient and enantioselective synthesis of loracarbef, starting from the unnatural amino acid (2.V,J .y)-2-amino-3-hydroxy-6-heptenoic acid <2000T5667, 2003TL5991> (Scheme 30). The cyclization step from monocyclic... 

Key Mechanism 22-12 The Claisen Ester Condensation 1071 22-13 The Dieckmann Condensation A Claisen Cyclization 1074 22-14 Crossed Claisen Condensations 1074 22-15 Syntheses Using /3-Dicarbonyl Compounds 1077 22-16 The Malonic Ester Synthesis 1079 22-17 The Acetoacetic Ester Synthesis 1082 22-18 Conjugate Additions The Michael Reaction 1085 Mechanism 22-13 1,2-Addition and 1,4-Addition (Conjugate Addition) 1085... 

Many of the standard methods of C-C bond formation in aliphatic systems can be extended to heterocyclic systems, e.g., the Dieckmann reaction (cf. 66 67) and alkylation of active methylene compounds (e.g., 68 69). An example of the application of the Dieckmann reaction to the preparation of 3-thiepanone 70 is shown in Scheme 42 <1952JA917>. Several more recent examples of applications of the Dieckmann condensation in the synthesis of substituted 4- and 3-piperidones are discussed in CHEC-III . 

A synthesis of 4-hydroxy-substituted TIQ has been developed in connection with plant isoquinolines (169,170), and the glycine ester route used for a similar purpose (171) is shown in Fig. 23. Reaction of the benzyl bromide 85 with N-methylglycine ester gave 86 the ketoester 87 was obtained on Dieckmann condensation. Alkaline hydrolysis of ester 87 followed by treatment with mineral acid gave ketone 88 alcohol 89 was obtained on reduction of 88 with sodium borohydride. 

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