A Concise Semisynthesis of Hederagonic Acid: C–H Activation in Natural Product Synthesis (BestMasters)

Foreword
Preface
Contents
List of Figures
List of Schemes
List of Tables
List of Abbreviations
1 Introduction
	1.1 Hederagonic Acid
		1.1.1 Natural Occurrence
		1.1.2 Biological Activity
		1.1.3 Previous Syntheses
	1.2 C–H Activation
		1.2.1 Stoichiometric C–H Oxidation
			1.2.1.1 Baldwin’s Cyclopalladation Reaction
		1.2.2 Catalytic C–H Oxidation
			1.2.2.1 Palladium Catalysed C–H Acetoxylation
2 Results and Discussion
	2.1 Objectives
	2.2 Preliminary Results
		2.2.1 Halolactone Oxime
			2.2.1.1 Chlorolactone Oxime
		2.2.2 C–H Activation at position C-23
			2.2.2.1 Palladium Catalysed C–H Acetoxylation
		2.2.3 Deacetylation and Deoximation
		2.2.4 Retro-halolactonisation
	2.3 Optimisation of the Synthetic Sequence
		2.3.1 Halolactone Oxime
			2.3.1.1 Chlorolactone Oxime
			2.3.1.2 Bromolactone Oxime
		2.3.2 C–H Activation at position C-23
			2.3.2.1 Palladium Catalysed C–H Acetoxylation
			2.3.2.2 Copper Catalysed C–H Hydroxylation
		2.3.3 Deacetylation and Deoximation
		2.3.4 Retro-halolactonisation
	2.4 Final Synthetic Route to Hederagonic Acid
		2.4.1 Economic Considerations
	2.5 Summary and Outlook
3 Experimental Section
	3.1 General Information
	3.2 Experimental Procedures
		3.2.1 12α-Chloro-3β-hydroxyolean-28,13β-olide (26a)
		3.2.2 12α-Bromo-3β-hydroxyolean-28,13β-olide (26b)
		3.2.3 12α-Chloro-3-oxo-olean-28,13β-olide (27a)
		3.2.4 12α-Bromo-3-oxo-olean-28,13β-olide (27b)
		3.2.5 12α-Chloro-3-(hydroxyimino)-olean-28,13β-olide (6a)
		3.2.6 12α-Bromo-3-(hydroxyimino)-olean-28,13β-olide (6b)
		3.2.7 12α-Chloro-3-(methoxyimino)-olean-28,13β-olide (29a)
		3.2.8 23-Acetoxy-3-(acetoxyimino)-12α-chloro-olean- 28,13β-olide (7a)
		3.2.9 23-Acetoxy-3-(acetoxyimino)-12α-bromo-olean- 28,13β-olide (7b)
		3.2.10 12α-Bromo-23-hydroxy-3-oxo-olean-28,13β-olide (8b)
		3.2.11 Hederagonic acid (23-Hydroxy-3-oxo-olean-12-en-28-oic acid) (1)
References and Notes