124355-75-5Relevant academic research and scientific papers
Synthesis and reactions of terpenyl diselenides functionalized with phenyl and naphthyl groups
?cianowski, Jacek,Szumera, Jakub,Kleman, Patryk,Pacu?a, Agata J.
, p. 238 - 245 (2016)
An efficient methodology for the synthesis of chiral terpenyl diselenides functionalized with phenyl and naphthyl groups has been developed. Using the reaction of sodium diselenide with terpenyl tosylates and chlorides, the corresponding diselenides derived from 8-phenyl menthol and isopinocampheol modified at the 10-position were obtained. Diselenides were transformed into electrophilic selenium reagents and tested in the asymmetric selenenylation of styrene. The effect of aryl groups on the enantioselectivity of the addition reaction was examined.
Hydroboration. 91. Improved Procedure for the Synthesis of Optically Pure Bis-adducts, N,N,N',N''-Tetramethylethylenediamine-2-organylapoisopinocampheylboranes, from the Corresponding 2-Organylapopinenes of Lower Optical Purity. Conversion of These Adducts into 2-Organylapoisopinocamp...
Brown, Herbert C.,Dhokte, Ulhas P.
, p. 2365 - 2369 (2007/10/02)
The higher analogues of α-pinene, such as 2-ethyl-, 2-n-propyl-, 2-isobutyl-, 2-phenyl-, and 2-isopropylapopinenes, were treated with borane-methyl sulfide (BMS) in the stoichiometry of 1.2:1, respectively, in anhydrous tetrahydrofuran (THF) at 25 deg C, obtaining an equilibrium mixture of 2-organylapoisopinocampheylboranes (2-R-apoisopinylborane, RapBH2) as major and bis(2-organylapoisopinocampheyl)borane as minor constituents.Treatment of the equilibrium mixture of boranes with tetramethylethylenediamine (TMEDA) at 34 deg C readily and selectively provided the optically pure bis(2-organylapoisopinocampheylborane)*TMEDA adducts, (RapBH2)2*TMEDA, in satisfactory yield.This reaction is quite general and appears to be broadly applicable to the conversion of the sterically bulkier 2-organylapopinenes (2-R-apopinenes) with widely varied steric requirements and lower optical purity (87-92percent ee) into the corresponding optically pure (RapBH2)2*TMEDA derivatives, approaching >/= 99percent ee.Treatment of the crystalline bis-adduct in ethyl ether with BF3*EE precipitates (BF3)2*TMEDA and provides RapBH2 of essentially >/= 99percent ee, enantiomerically purer than the 2-R-apopinenes of 87-92percent ee utilized for these preparations.
New Chiral Auxiliaries Derived from β-Pinene: Their Use in the Asymmetric Reduction of β-Keto-Esters
Vasconcellos, Mario Luiz,d'Angelo, Jean,Desmaele, Didier,Costa, Paulo R. R.,Potin, Dominique
, p. 353 - 356 (2007/10/02)
3-Ketobutyrates 6, derived from chiral auxiliary alcohols 5 - themselves efficiently prepared from β-pinene 4 - were reduced with zinc borohydride, giving 3-hydroxybutyrates 7 with 2-70percent de, depending on the nature of aryl group in alcohols 5.
Hydroboration. 85. Synthesis and Hydroboration of (-)-2-Phenylapopinene. Comparison of Mono(2-phenylapoisopinocampheyl)borane with Its 2-Methyl and 2-Ethyl Analogues for the Chiral Hydroboration of Representative Alkenes
Brown, Herbert C.,Weissman, Steven A.,Perumal, P. T.,Dhokte, U. P.
, p. 1217 - 1223 (2007/10/02)
The dehydration of (+)-2-phenylnopinol with POCl3 provides a new chiral ligand, (-)-2-phenylapopinene (87percent ee), with higher steric requirements than those of α-pinene or its 2-ethyl analogue.Hydroboration of (-)-2-phenylapopinene with BH3*SMe2 (BMS) (1.2:1 ratio, respectively) provides an equilibrium mixture of the mono(2-phenylapoisopinocampheyl)borane (PapBH2) and the corresponding dialkylborane.Treatment of this mixture with tetramethylethylenediamine (TMEDA) precipitates crystalline (PapBH2)*TMEDA.Liberation of the PapBH2 using BF3*OEt2 provides the monoalkylborane in >99percent ee, thus providing the required reagent in significantly higher optical purity than the starting olefin.Hydroboration of a series of representative olefins using PapBH2 at -25 deg C, followed by oxidative workup, provides the corresponding chiral alcohols in unexpectedly lower enantiomeric purities than those obtained from the 2-methyl and 2-ethyl analogues under identical conditions.Liberation of the starting auxiliary from the borane reagent provides (-)-2-phenylapopinene of >99percent ee.The hydroboration of (-)-2-phenylapopinene with 9-borabicyclononane (9-BBN) at 28 deg C in THF proceeds at an extremely retarded rate compared to its 2-methyl and 2-ethyl analogues.Fortunately, this lack of reactivity is easily circumvented by reacting PapBH2 with 1,5-cyclooctadiene at room temperature for 1 h, followed by thermal isomerization to provide the desired trialkylborane.
