132617-05-1Relevant articles and documents
Synthesis of 3-exo-aroylhexahydroindoles via sequential gold(I)-catalyzed claisen-type rearrangement-epimerization reactions of cis -4-[ N -Tosyl- N -(3-arylprop-2-ynyl)amino]cyclohex-2-en-1-ols
Liang, Chia-Jung,Jiang, Xuan-Yi,Yeh, Ming-Chang P.
, p. 2220 - 2224 (2014)
A two-step process for the synthesis of 3-exo-aroylhexahydroindoles is described. cis-4-[N-Tosyl-N-(3-arylprop-2-ynyl)amino]cyclohex-2-en-1-ols were cycloisomerized with a catalytic amount of chloro(triphenylphosphine)gold(I)/ silver(I) hexafluoroantimonate (AuPPh3Cl/AgSbF6); subsequent base treatment of the crude mixture provided 3-exo- aroylhexahydroindoles in good yields and complete stereoselectivity. A key step involving a 9-endo-dig attack of the hydroxyl group onto the gold-activated alkyne is proposed. The resulting allyl vinyl ether intermediate underwent a gold-assisted [3,3]-sigmatropic rearrangement to form 3-exo-3- aroylhexahydroindole derivatives. Georg Thieme Verlag Stuttgart. New York.
The total synthesis of (+)-petasin and (+)-isopetasin
Witschel, Matthias C.,Bestmann, Hans Jürgen
, p. 107 - 112 (1997)
Petasin 1 and isopetasin 2, anti-inflammatory and analgesic components of the butterbur (Petasites hybridus), were prepared for the first time in a short and enantioselective synthesis. The key steps were a Michael addition/alkylation (7 → 8), an enamine alkylation to give 9 and a cyclization with N-phenyliminoketenylidenetriphenylphosphorane 11 (10 → 15).
ENZYMATIC PREPARATION OF (3S,6R) AND (3R,6S)-3-HYDROXY-6-ACETOXYCYCLOHEX-1-ENE
Harris, Keith J.,Gu, Qu-Ming,Shih, Yun-Er,Girdaukas, Gary,Sih, Charles J.
, p. 3941 - 3944 (1991)
Pseudomonas cepacia lipase-catalyzed enantioselective hydrolysis of 2 in water afforded (3S,6R)-3.The antipode (3R,6S)-3 was prepared by enantioselective acylation of 4 using the same enzyme.
Iron(II) Halide Promoted Cyclization of Cyclic 2-Enynamides: Stereoselective Synthesis of Halogenated Bicyclic γ-Lactams
Yeh, Ming-Chang P.,Shiue, Yuan-Shin,Lin, Hsin-Hui,Yu, Tzu-Yu,Hu, Ting-Chia,Hong, Jia-Jyun
, p. 2407 - 2410 (2016/06/09)
A simple and mild process was developed for the highly stereoselective synthesis of halogenated bicyclic [4.3.0] and [3.3.0] γ-lactams, possessing four stereocenters, from easily available cyclic 2-enynamides. The reaction required only an inexpensive iron(II) halide under dry air and was tolerant of aryl, heteroaryl, and alkyl groups at the alkyne terminus.
The thio-adduct facilitated, enzymatic kinetic resolution of 4-hydroxycyclopentenone and 4-hydroxycyclohexenone
O'Byrne, Aisling,Murray, Cian,Keegan, Dearbhla,Palacio, Carole,Evans, Paul,Morgan, Ben S.
supporting information; experimental part, p. 539 - 545 (2010/05/11)
The addition of 3,4-dimethoxybenzyl thiol 8, as a benzyl thiol surrogate, to racemic 4-hydroxycyclopent-2-enone 2 and 4-hydroxycyclohex-2-enone 15 gave the corresponding cis-adducts (±)-3-(3,4-dimethoxybenzylthio)-4- hydroxycyclopentanone 4b and (±)-3-(3,4-dimethoxybenzylthio)-4- hydroxycyclohexanone 16 with good diastereocontrol. In both cases, subsequent treatment with vinyl acetate, in the presence of a lipase enabled enantiomer resolution. Thus, (+)-16 and the acetate of its enantiomer, (-)-(1R,2S)-2-(3,4- dimethoxybenzylthio)-4-oxocyclohexyl acetate, (-)-17 were isolated in 98% enantiomeric excess. Based on the 1,4-dioxygenation pattern, (-)-17 can be used to prepare both enantiomers of 4-(tert-butyldimethylsilyloxy)cyclohex-2-enone 19. Firstly, saponification, with a sub-stoichiometric amount of NaOMe, followed by a one-pot silyl ether formation-sulfide elimination sequence gave (+)-19. Then using the same starting material a 6-step sequence, featuring a diastereoselective NaBH4 reduction and a Cope-type sulfoxide elimination, gave (-)-19.
Synthetic studies toward the construction of the cis-decalin portion of superstolides A and B. Application of a sequential double Michael reaction and an anionic oxy-Cope rearrangement
Hua, Zhengmao,Yu, Wensheng,Su, Mei,Jin, Zhendong
, p. 1939 - 1942 (2007/10/03)
(Chemical Equation Presented) A highly convergent strategy for the asymmetric synthesis of the cis-decalin portion of the antitumor macrolide superstolide A was developed. The key reactions in our approach involve a sequential double Michael reaction and
Pyrrolizidine alkaloids by intramolecular palladium-catalysed allylic alkylation: Synthesis of (±)-isoretronecanol
Lemaire, Sebastien,Giambastiani, Giuliano,Prestat, Guillaume,Poli, Giovanni
, p. 2840 - 2847 (2007/10/03)
An efficient and stereoconvergent approach to 3-substituted hexahydroindol-2-one derivatives by palladium-catalysed intramolecular allylic alkylation has been developed. Subsequently, the straightforward conversion of the hexahydroindol-2-one 7d into the alkaloid (±)-isoretronecanol has been performed. The synthesis entails 11 steps starting from 1,3-cyclohexadiene, affording the final target in a 29% overall yield. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Palladium-catalysed enantiodivergent synthesis of cis- and trans-4-aminocyclohex-2-enols
Gatti, Roberto G. P.,Larsson, Anna L. E.,Baeckvall, Jan-E.
, p. 577 - 584 (2007/10/03)
Enantiomerically pure cis- and trans-4-aminocyclohex-2-enols are prepared from cyclohexa-1,3-diene via (-)-cis-(1R,4S)-4-acetoxycyclohex-2-enol (-)-2a using palladium(0) chemistry. Benzylamine and diethylamine are tested in the Pd0-catalysed allylic amination reactions. Since acetate is too slow as a leaving group and gave considerable amounts of side products, a number of leaving groups have been investigated. Of these phosphinate and 2,4-dichlorobenzoate are excellent leaving groups and result in efficient and highly stereoselective reactions; chloride as allylic leaving group also gives good results. By variation of the leaving group and proper choice of the protecting group it is possible to synthesise all four stereoisomers of 4-aminocyclohex-2-enol in good yield and high enantiomeric excess.
A Rule To Predict Which Enantiomer of a Secondary Alcohol Reacts Faster in Reactions Catalyzed by Cholesterol Esterase, Lipase from Pseudomonas cepacia, and Lipase from Candida rugosa
Kazlauskas, Romas J.,Weissfloch, Alexandra N. E.,Rappaport, Aviva T.,Cuccia, Louis A.
, p. 2656 - 2665 (2007/10/02)
The enantioselectivity of the title enzymes for more than 130 esters of secondary alcohols is correlated by a rule based on the sizes of the substituents at the stereocenter.This rule predicts which enantiomer of a racemic secondary alcohol reacts faster for 14 of 15 substrates of cholesterol esterase (CE), 63 of 64 substrates of lipase from Pseudomonas cepacia (PCL), and 51 of 55 cyclic substrates of lipase from Candida rugosa (CRL).The enantioselectivity of CRL for acyclic secondary alcohols is not reliably predicted by this rule.This rule implies that the most efficiently resolved substrates are those having substituents which differ significantly in size.This hypothesis was used to design syntheses of two chiral synthons: esters of (R)-lactic acid and (S)-(-)-4-acetoxy-2-cyclohexen-1-one, 70.As predicted, the acetate group of the methyl ester of lactyl acetate was hydrolyzed by PCL with low enantioselectivity because the two substituents, CH3 and C(O)OCH3, are similar in size.To improve enantioselectivity, the methyl ester was replaced by a t-butyl ester.The acetate group of the tert-butyl ester of lactyl acetate was hydrolyzed with high enantioselecticity (E > 50).Enantiomerically pure (R)-(+)-tert-butyl lactate (>98percent ee, 6.4 g) was prepared by kinetic resolution.For the second example, low enantioselectivity (E 65) using either CE or CRL.Enantiomerically pure 70 (98percent ee) was obtained after removal of the bromines with zinc and oxidation with CrO3/pyridine.
