The mechanistic study and synthetic applications of the base treatment in the ozonolytic reactions

Dedicated to Professor Albert Eschenmoser on the occasion of his 75th birthday Macrocyclic lactonic alkaloids found in the pupal secretions of two species of a coccinellid beetle (genus Epilachna) were prepared in enantiomerically pure form via an efficient synthetic route using enantiomerically pure a-amino acids as chiral-pool starting materials. Macrocycles with rings containing up to 98 atoms were synthesized in good yield using Mukaiyamas macrolactonization conditions.Introduction. ± While natural-products chemistry is, by most criteria, a mature field, the chemical ecological approach to natural-products chemistry continues to uncover structural novelty among the pheromones, allomones, and kairomones that govern a very wide range of biologically significant interactions in nature. The macrocyclic alkaloids, the synthesis of which is the subject of this communication, were, in fact, discovered as the result of a biorational investigation.Since a pupating insect may be sessile for a period of up to a week or more, this stage in an insects life cycle manifests a heightened risk of predation. It is not surprising, therefore, that the pupae of many beetle species possess protection in various forms, most commonly spines or concealing coloration [1], but in some cases chemical defenses as well. The pupae of several species of ladybird beetle (family Coccinellidae) are coated with glandular hairs, the tips of which secrete droplets of a clear liquid that repels predators. Analysis of the defensive secretion exuded by pupae of the Mexican bean beetle Epilachna varivestis revealed it to consist principally of the macrocyclic lactone epilachnene ( (5Z)-11-propyl-12-azatetradec-5-en-14-olide (10Z)-5-propyl-1-oxa-4-azacyclopentadec-10-en-15-one; 1) along with minor amounts of related compounds [2]. Encouraged by this interesting result, we undertook the analysis of the pupal defensive alkaloids of related coccinellids and found that the pupa of Epilachna borealis (the squash beetle) is protected by a much more complex exudate consisting of a combinatorial library of very-large-ring oligomeric alkaloids [3].

show abstract

“…generally being sufficient to affect a complete transformation. For a discussion of a likely mechanism for this reaction, see [8].…”

mentioning

confidence: 99%

Synthesis of Macrocyclic Insect-Derived Alkaloids

Farmer

Schroeder

Meinwald

2000

HCA

View full text Add to dashboard Cite

show abstract

“…9 Without purification of unstable aldehydes 18 and 19, an intramolecular aldol reaction with potassium hydroxide in ethanol at 50 C afforded bicyclic hydroxyketones 11 and 20 in 80% yield. In contrast, the aldol reaction in methanol led to acetal 21, which regenerated keto aldehydes 18 and 19 by acid-catalyzed hydrolysis.…”

Section: Synthesis Of Common Intermediate 10mentioning

confidence: 99%

“…However, the absolute stereochemistries of drechslerines have not been fully discussed. 2 Synthetic studies of sesquiterpenoids with the bicyclo[3.2.1]octane core have already been conducted: first, in the total synthesis of helminthosporal (8) 3 by Corey and Nozoe in 1965, 3a and subsequently by other groups in the total synthesis of sativene (9), 4 which has an antipodal core of helminthosporal (8). Since then, synthetic studies in this area have been interrupted over two decades because new natural products have not been isolated.…”

Section: Introductionmentioning

confidence: 99%

First total syntheses of bicyclic marine sesquiterpenoids drechslerines A and B

Hagiwara¹,

Fukushima²,

Kinugawa³

et al. 2011

Tetrahedron

View full text Add to dashboard Cite

“…Ozonolysis of 2, followed by the usual treatment with Me 2 S, resulted in a moderate yield (50%) of 3. This yield was somewhat improved (77%) when the ozonolysis was followed by fragmentation of the transient rather stable ozonide in the presence of Et 3 N [18]. The subsequent transformation of 3 into the iodo-alkenyl derivative 4 (86%) according to Takai et al [19] was uneventful (Scheme 2).…”

mentioning

confidence: 93%

The First Chemical Synthesis of a Cyclodextrin Heteroduplex

Bistri

Lecourt

Mallet

et al. 2004

Chemistry & Biodiversity

View full text Add to dashboard Cite

The synthesis of the first heteroduplex of cyclodextrin (CD) 11, i.e., a compound in which the two primary rims of alpha- and beta-CDs are doubly connected, was achieved. The selected strategy involved a Sonogashira coupling of propargylated beta-CD 6 and iodo-alkenyl alpha-CD 4 to singly connect the two CDs. A ring-closing metathesis (RCM) of the heterodimer 9 afforded the second bridge, final deprotection and reductions giving access to 11.

show abstract

The mechanistic study and synthetic applications of the base treatment in the ozonolytic reactions

Cited by 73 publications

References 27 publications

Synthesis of Macrocyclic Insect-Derived Alkaloids

Synthesis of Macrocyclic Insect-Derived Alkaloids

First total syntheses of bicyclic marine sesquiterpenoids drechslerines A and B

The First Chemical Synthesis of a Cyclodextrin Heteroduplex

Contact Info

Product

Resources

About