Catalytic Asymmetric Addition of Polyfunctional Dialkylzincs to .beta.-Stannylated and .beta.-Silylated Unsaturated Aldehydes

Ostwald, R.; Chavant, Pierre Y.; Stadtmueller, Heinz; Knöchel, Paul

doi:10.1021/jo00094a027

Cited by 116 publications

(50 citation statements)

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“…The necessary enantioselective in- troduction of an ethyl group was performed according to Knochel et al [29] by using a defined mixture of ZnEt 2 , Ti-A C H T U N G T R E N N U N G (OiPr) 4 and the enantiopure diamino ligand 57. [30] The desired compound 58 was isolated in 96 % yield with 98 % ee. The addition step was followed by a simple protection-deprotection procedure to give 59 in 85 % yield over two steps.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Novel Spinosyn A Analogues by Pd‐Mediated Transformations

Tietze

Brasche

Grube

et al. 2007

Chemistry A European J

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The concept of modern crop protection demands for a continuous supply of new or modified established pesticides to avoid the development of serious resistances. Recent reports on the insecticidal spinosyns 1 and 2 show that also this class of pest managing agents is increasingly exposed to the formation of resistances. The synthesis of new derivatives is therefore highly desirable. We describe in this paper a convergent approach towards novel enantiopure spinosyn A analogues of type 3, which is based on investigations of structure-activity relationships and employs a twofold Heck reaction as key step for the preparation of the tricyclic backbone assembly.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Novel Spinosyn A Analogues by Pd‐Mediated Transformations

Tietze

Brasche

Grube

et al. 2007

Chemistry A European J

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“…[38] A solution of n-butyllithium in hexanes (21.70 mL, 33.6 mmol, 2.4 equiv.) was added to a suspension of CuCN (1.51 g, 16.8 mmol, 1.2 equiv.)…”

Section: Discussionmentioning

confidence: 99%

The Application of [γ‐(Silyloxy)allylidene]ditin to the Efficient Synthesis of the Chromophore of the Neocarzinostatin Dihydroxycyclopentene‐Based Dienediyne Core

Madec¹,

Férézou²

2005

Eur J Org Chem

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1‐(tert‐Butyldimethylsilyl)oxy‐3,3‐bis(tributylstannyl)propene (5), a versatile gem‐dimetallic allylic synthon accessible through various synthetic routes, has been condensed with (trimethylsilyl)propiolaldehyde to give the fully functionalised acyclic vinyltin compound 9h, which is a precursor of the complex dihydroxycyclopentene sub‐unit of neocarzinostatin chromophore (NCS) 1. Subsequent transformation into the geminal (E)‐α‐chloro‐(Z)‐α‐iodovinylic intermediate 20, followed by a palladium‐catalysed carbometallation/cyclisation reaction including in situ trapping with either (tributylstannyl)acetylene or the more functionalised 3,3‐diethoxy‐1‐(tributylstannyl)prop‐1‐yne delivered the corresponding alkyne‐substituted 4‐chloro‐1,2‐bis(silyloxy)cyclopent‐3‐enes 21 or 22, respectively. Chlorocyclopentene 21 was subsequently easily transformed into the target dienediyne adduct 23 by Sonogashira condensation with trimethylsilylacetylene. This diastereoselective process is efficient with only six steps and an overall 26 % yield from the allylic ditin precursor 5. More than just an NCS building block, the final acyclic dihydroxycyclopentene‐based dienediyne is also a seco analogue of the NCS chromophore. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…[30] The original procedure for the catalyst preparation was devised by Ohno and Kobayashi [31] and was subsequently modified by Walsh. [32] In the Ohno and Kobayashi method, 1 and Ti-A C H T U N G T R E N N U N G (OiPr) 4 were first heated in toluene at 40 8C for 20 min, then diethylzinc was added at À78 8C, followed by benzaldehyde.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Asymmetric Amplification by Kinetic Resolution Using A Racemic Reagent: Example in Amine Acetylation

Satyanarayana

Kagan

2006

Chemistry A European J

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The reaction of a racemic reagent on a mixture of enantiomers with small ee (ee=enantiomeric excess) has been studied for amine acylation. A substantial asymmetric amplification could be realized, for example, from 67 to >95.5 ee. The combination of asymmetric amplifications is subsequently discussed. Two sequential asymmetric amplifications, one using a racemic reagent and another using a positive nonlinear effect allowed us to start from 1.5 % ee and end with a large amount of a product of 97 % ee.

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Catalytic Asymmetric Addition of Polyfunctional Dialkylzincs to .beta.-Stannylated and .beta.-Silylated Unsaturated Aldehydes

Cited by 116 publications

References 0 publications

Synthesis of Novel Spinosyn A Analogues by Pd‐Mediated Transformations

Synthesis of Novel Spinosyn A Analogues by Pd‐Mediated Transformations

The Application of [γ‐(Silyloxy)allylidene]ditin to the Efficient Synthesis of the Chromophore of the Neocarzinostatin Dihydroxycyclopentene‐Based Dienediyne Core

Asymmetric Amplification by Kinetic Resolution Using A Racemic Reagent: Example in Amine Acetylation

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