The Synthesis and Decomposition Kinetics of Some para-Substituted trans-γ-Benzylidenebutyryl Peroxides. The Excess α,γ-Bis(biphenylene)- β-phenylallyl Method for the Determination of Initiator Kinetics<sup>1</sup>

Lamb, Robert C.; Spadafino, Leonard P.; Webb, Ronald G.; Smith, Earl B.; McNew, W. E.; Pacifici, J. Grady

doi:10.1021/jo01339a031

Cited by 8 publications

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“…an 8% overall yield has been obtained. 4,10,17 This was mainly due to the application of the 'clean' Wittig reaction, which gave the pure Z-configured acid 3 starting precursor, while in the previously published reactions, [10][11][12][13] a complex mixture of Econfigured acid and derivatives was obtained. Furthermore, our synthetic design has revealed a conspicuous example that demonstrates that the efficiency of a total synthetic approach can markedly depend on the nature (geometry) of the selected starting precursors, which can themselves be prepared in high yield in a cleaner manner.…”

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“…Similar synthetic approaches have been described by Rosenblum et al 10 The starting compound, (E)-5-(4-fluorophenyl)pent-4-enoic acid, has been synthesized by several methods. [10][11][12][13] Interestingly, the synthesis of (Z)-5-(4-fluorophenyl)pent-4-enoic acid and its use has not been reported yet. Although the synthesis of ezetimibe (1) via (E)-5-(4-fluorophenyl)pent-4-enoic acid 4,10 appears to be appealing, an overall yield of below 10% and the tedious unselective preparation of the E-configured acid precursor makes this approach unsuitable for practical use.…”

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(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

Sova¹,

Mravljak²,

Kovač³

et al. 2010

Synthesis

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A convenient and efficient total synthesis of ezetimibe, an intestinal cholesterol absorption inhibitor and useful anticholesteremic agent, is described. Based on (Z)-5-(4-fluorophenyl)pent-4-enoic acid as a starting compound, and taking the synthesis through further Z-configured intermediates, the total yield is remarkably increased, compared with the use of the corresponding E-configured starting substances or intermediates.

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(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

Sova¹,

Mravljak²,

Kovač³

et al. 2010

Synthesis

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Reductions by Metal Alkoxyaluminum Hydrides

Málek

1985

Organic Reactions

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Since the discovery of the reducing properties of diborane (1939), alkali metal borohydrides (1943), and alkali metal aluminohydrides (1946) by H. I. Schlesinger, H. C. Brown, W. G. Brown, and co‐workers, considerable effort has been expended to enhance the versatility and selectivity of these widely used hydride reagents. Whereas diborane exhibits medium reaction large differences exist between sodium borohydride and lithium aluminum hydride. In contrast to the reducing action of sodium borohydride, limited originally to aldehydes, ketones, and acid chlorides, lithium aluminum hydride readily attacks almost all reducible groups. The first progress in bridging this gap in reactivity can be traced to the availability of reagents that are easily prepared by addition of Lewis acids such as boron and aluminum halides to sodium borohydride and lithium aluminum hydride; in this manner diborane, chloroaluminum hydrides, and aluminum hydride have been made accessible as reducing agents. Parallel development led to sodium alkoxyborohydrides with generally higher reactivity than the parent hydride and to alkoxyaluminum hydrides, with markedly lower reactivity and increased chemoselectivity. On the other hand, the reducing capability of sodium borohydride and lithium aluminum hydride has been enhanced by the use of metal salt–hydride systems. A large number of other complex metal hydrides have gained importance as selective reducing agents: lithium aluminum hydride–nitrogen base complexes, sodium cyanoborohydride, lithium cyanoborohydride, sulfurated sodium borohydride, zinc borohydride, diisobutylaluminum hydride, alkylaluminum compounds such as triisobutylaluminum, and tri‐ n ‐butyltin hydride. Sterically hindered organoboranes such as lithium tri‐ sec ‐butylborohydride (L‐Selectride) exhibit excellent selectivity in reduction reactions. High asymmetric induction can be achieved with some chiral organoboranes. Lithium triethylborohydride (Super‐Hydride) is a selective and exceptionally powerful reducing agent. These complex metal hydrides often provide better regio‐ and stereoselectivities than those achieved with alkoxy‐substituted hydrides; nevertheless, the alkoxyhydrides are readily available and continue to be widely used as reducing agents. The purpose of this chapter is to present a critical review of reductions of the following compounds by metal alkoxyaluminum hydrides, alkoxyaluminum hydrides, and chiral metal alkoxyaluminohydride complexes: hydrocarbons, peroxides, ozonides, halogen compounds, unsaturated alcohols, aromatic alcohols, ethers, 1,2‐oxides, aldehydes, ketones, quinones, acetals, and ketals. The literature is covered through December 1981. Important papers that appeared through September 1982 are also reviewed. Some reactions relating to other than reducing properties of these hydrides are included for completeness. The emphasis is on the scope, limitations, and synthetic utility of the hydrides in reduction reactions and on the optimum conditions for their application as reducing agents. Currently accepted views of reaction mechanisms are discussed. Comparisons with reductions by other complex metal hydrides are limited to the most important transformations of the functional groups.

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Decomposition Rates of Organic Free Radical Initiators

Dixon

1999

The Wiley Database of Polymer Properties

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The Synthesis and Decomposition Kinetics of Some para-Substituted trans-γ-Benzylidenebutyryl Peroxides. The Excess α,γ-Bis(biphenylene)- β-phenylallyl Method for the Determination of Initiator Kinetics¹

Cited by 8 publications

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(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

Reductions by Metal Alkoxyaluminum Hydrides

Decomposition Rates of Organic Free Radical Initiators

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The Synthesis and Decomposition Kinetics of Some para-Substituted trans-γ-Benzylidenebutyryl Peroxides. The Excess α,γ-Bis(biphenylene)- β-phenylallyl Method for the Determination of Initiator Kinetics1

Cited by 8 publications

References 0 publications

(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

(Z)-5-(4-Fluorophenyl)pent-4-enoic Acid: A Precursor for Convenient and Efficient Synthesis of the Antihypercholesterolemia Agent Ezetimibe

Reductions by Metal Alkoxyaluminum Hydrides

Decomposition Rates of Organic Free Radical Initiators

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The Synthesis and Decomposition Kinetics of Some para-Substituted trans-γ-Benzylidenebutyryl Peroxides. The Excess α,γ-Bis(biphenylene)- β-phenylallyl Method for the Determination of Initiator Kinetics¹