Domino Mukaiyama–Michael reactions in the synthesis of polycyclic systems

Sarabèr, Florence C.E.; Dratch, Svetlana; Bosselaar, Geke; Jansen, B. J. M.; Groot, Aede de

doi:10.1016/j.tet.2005.11.059

Cited by 18 publications

(15 citation statements)

References 43 publications

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“…tert-Butyldimethylsilyloxy cyclohexene (12). 1 10,11 (the shift δ 0.01 given for nine hydrogens of tert-butyl group in ref. 10 is most likely a typographic error).…”

mentioning

confidence: 99%

The introduction of a double bond on the steroid skeleton – The preparation of enol silyl ether derivatives from vicinal diols

Marek

Klepetářová

Elbert

2011

Collect. Czech. Chem. Commun.

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The ways of converting steroid vicinal diol into an unsaturated derivative were studied with the intention of preparing suitable precursors for the introduction of deuterium or tritium into the molecules of brassinosteroids. The model vicinal diol compound, 2α,3α-dihydroxy-5α-pregnane-6,20-dione (3), was converted with high regioselectivity to the α-hydroxy ketone derivative, 2α-hydroxy-5α-pregnane-3,6,20-trione (8), in a 75% yield. The attempts to convert α-hydroxy ketone 8 to the dioxolene derivative, 2α,3α-(isopropylidenedioxy)-5α-pregn-2-ene-6,20-dione (6), failed. The conditions for the conversion of ketone to the corresponding enol trialkylsilyl ether were optimized using cyclohexanone as a model compound. The best and reproducible results were obtained by using tert-butyldimethylsilyl trifluoromethansulfonate (TBDMSiOTf) as the silylating reagent and triethylamine as the base. Under these conditions, the 3,6,20-trione (8) was converted to 2,3-bis(tert-butyldimethylsilyloxy)-5α-pregn-2-ene-6,20-dione (14) with a 66% yield.

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“…tert-Butyldimethylsilyloxy cyclohexene (12). 1 10,11 (the shift δ 0.01 given for nine hydrogens of tert-butyl group in ref. 10 is most likely a typographic error).…”

mentioning

confidence: 99%

The introduction of a double bond on the steroid skeleton – The preparation of enol silyl ether derivatives from vicinal diols

Marek

Klepetářová

Elbert

2011

Collect. Czech. Chem. Commun.

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“…Synthesis of the title compound is described elsewhere (Sarabè r et al, 2005). Crystals of (I) suitable for diffraction experiments were obtained by evaporation of a solution of the title compound in hexane.…”

Section: Methodsmentioning

confidence: 99%

“…The structure of the title compound, (I), was determined in the course of our investigations toward the synthesis of polycyclic systems using Mukaiyama reactions (Sarabè r et al, 2005). The molecular structure of (I) is displayed in Fig.…”

Section: Commentmentioning

confidence: 99%

(3R,5S,6S,8R,10S)-8-Acetyl-7-hydroxy-3-isopropenyl-10-methylperhydrophenanthren-1-one

et al. 2005

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Key indicatorsSingle-crystal X-ray study T = 150 K Mean (C-C) = 0.004 Å R factor = 0.046 wR factor = 0.099 Data-to-parameter ratio = 9.0 CommentThe structure of the title compound, (I), was determined in the course of our investigations toward the synthesis of polycyclic systems using Mukaiyama reactions (Sarabè r et al., 2005). The molecular structure of (I) is displayed in Fig. 1. Selected geometric parameters are given in Table 1. All six-membered rings are in chair conformations, and the relevant asymmetry parameters (Duax & Norton, 1975) are all less than 10. The absolute configuration of atom C5 was assigned as S. The other chiral centres, C3, C6, C7, C8 and C10, have configurations R, S, S, R and S, respectively.The title compound displays an intramolecular hydrogen bond between the hydroxyl (O19) and acetyl (O21) groups (Fig. 1). The packing displays no intermolecular hydrogen bonds or short C-HÁ Á ÁA contacts. A plot of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The dashed line indicates a hydrogen bond.

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“…The cycloaddition reaction was also carried out in the presence of such catalysts as ZnCl 2 [4], ZnBr 2 [17], EtAlCl 2 , TiCl 4 [21], BF 3 · Et 2 O [18,24], AlCl 3 -PhNO 2 in toluene [25,26], and 5 M LiClO 4 in Et 2 O [27]; the reactant ratio was 1 : 1, and methylene chloride or diethyl ether was used as solvent. The reaction of 1 with 2 in methylene chloride, catalyzed by ZnBr 2 , EtAlCl 2 , TiCl 4 , BF 3 · Et 2 O, or by AlCl 3 -PhNO 2 in toluene, afforded less than 1% of 3 and 4.…”

Section: Doimentioning

confidence: 99%

“…Unlike syntheses involving introduction of already finished D ring [11][12][13][14][15], including the chiral one [15][16][17][18][19][20][21], the use of levoglucosenone (1) as dienophile implies that, regardless of the cycloaddition result, the stereochemical structure of the adduct can be changed and subsequently modified toward estrone synthesis. Some intermediate products can be used to study structure-biological activity relationships.…”

mentioning

confidence: 99%