Auxiliary silicon in regioselective cobalt catalyzed protoberberine syntheses

HILLARD, R. L. III; Parnell, Carol A.; Vollhardt, K. Peter C.

doi:10.1016/s0040-4020(01)88589-6

Cited by 64 publications

(14 citation statements)

References 35 publications

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“…152 As illustrated in Figure 44B, annulation between the TMS-alkyne-containing diyne 104 and alkyne 105 promoted by one equivalent of CpCo(CO) 2 produced the tetracycle 106 in 58% yield as a single regioisomer. Here, the TMS-group of alkyne 105 was reasoned to play a critical role in the regiochemical course of the [2+2+2] reaction.…”

Section: Metallacycle-mediated Cross-coupling By [2+2+2]mentioning

confidence: 99%

Metallacycle-mediated cross-coupling in natural product synthesis

2016

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Section: Metallacycle-mediated Cross-coupling By [2+2+2]mentioning

confidence: 99%

Metallacycle-mediated cross-coupling in natural product synthesis

2016

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“…51,52 In 1983, they succeeded in applying Z 5 -cyclopentadienyldicarbonylcobalt in the cyclization of 1,2-bis(propargyl)-1,2,3,4-tetrahydroisoquinolines with alkynes. 53 This procedure provides a novel synthetic entry into various tetrahydroprotoberberine nuclei. By judicious choice of trimethylsilyl substituents, regiocontrol in the D-ring can be achieved.…”

Section: Six-membered and Other Heterocyclesmentioning

confidence: 99%

CHAPTER 5. Cobalt-Catalyzed Heterocycle Synthesis

2014

Catalysis Series

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Cobalt has the chemical configuration [Ar]4s 2 3d 7 and has oxidation states Co(II) and Co(III). Cobalt has many applications in a wide range of areas. In materials, cobalt is primarily used as the metal, for example, in the preparation of magnetic, wear-resistant and high-strength alloys. In biology, cobalt is the active center of coenzymes called cobalamins, the most common example of which is vitamin B 12 . As such, it is an essential trace dietary mineral for all animals. Cobalt in inorganic form is also an active nutrient for bacteria, algae and fungi. In chemistry, various cobalt compounds are used as oxidation catalysts in chemical reactions. Cobalt acetate is used for the conversion of xylene to terephthalic acid, the precursor to the bulk polymer poly(ethylene terephthalate). Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes and inks as 'drying agents' through the oxidation of drying oils. The same carboxylates are also used to improve the adhesion of steel to rubber in steel-belted radial tires. Cobalt-based catalysts are also important in reactions involving carbon monoxide. In this chapter, the applications of cobalt catalysts in the synthesis of heterocycles is discussed. Five-Membered HeterocyclesIn 1986, Pattenden and co-workers reported a cobalt-promoted oxidative freeradical cyclization of alkyl bromides, 1 by which functionalized butyrolactones were selectively formed in good yields. In 1990, a convenient method for the stereoselective preparation of trans-2-hydroxymethyltetrahydrofurans by the oxidative cyclization of 5-hydroxy-1-alkenes was developed by Inoki and Mukaiyama. 2 They used bis(1-morpholinocarbamoyl-4,4-dimethyl-1,3-pentanedionato)cobalt(II) [Co(modp) 2 ] as the catalyst with molecular oxygen as the RSC Catalysis Series No.

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“…Formation of the C-10,C-11-bond, the equivalent of construction of the aromatic ring D has been realized, to the best of our knowledge, once only until now by cobalt-catalyzed cooligomerization of tetrahydroisoquinoline diynes with acetylene derivatives [69]. A more convenient method for this purpose offers the current RCM procedures as demonstrated by the synthesis of the alkaloid gusanlung D 97d.…”

Section: C-10c-11-bond Formationmentioning

confidence: 99%

Recent Strategies for the Synthesis of Protoberberines and Protoberberine Type Compounds

Reimann

2009

COC

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The protoberberines are a widespread, important group of isoquinoline alkaloids. Due to the potent pharmacological and other bioactive properties they have achieved an increasing attention in medicinal chemistry and drug research. This article will give a brief structural classification of the protoberberines and related compounds, the biosynthesis, a compilation of new alkaloids isolated during the last decade including source, structure and analytical/spectral data. The main part of the present review is focused on recent synthesis pathways to the title compounds.

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Auxiliary silicon in regioselective cobalt catalyzed protoberberine syntheses

Cited by 64 publications

References 35 publications

Metallacycle-mediated cross-coupling in natural product synthesis

Metallacycle-mediated cross-coupling in natural product synthesis

CHAPTER 5. Cobalt-Catalyzed Heterocycle Synthesis

Recent Strategies for the Synthesis of Protoberberines and Protoberberine Type Compounds

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