cas 112022-81-8, (S)-3,3-Diphenyl-1-methylpyrrolidino[1,2-c]-1,3,2-oxazaborole

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An enantioselective approach to cytotoxic norcalamenenes via electron-transfer-driven benzylic umpolung of an arene tricarbonyl chromium complex
An efficient enantioselective total synthesis of (R)-1-isopropenyl-6-methoxy-7-methyl-1,2,3,4-tetrahydronaphthalene, the dehydro-analog of the cytotoxic norsesquiterpene (R)-7-demethyl-2-methoxycalamenene, was achieved in seven steps starting from 6-methoxytetralone. The synthesis exploits the specific reactivity and stereochemistry of planar chiral η6-arene-Cr(CO)3 complexes. In a key step, a Cr(CO)3-complexed benzylic anion, regioselectively generated by means of electron- transfer-driven benzylic umpolung, is diastereoselectively alkylated with acetyl chloride.
Schmalz, Hans-Guenther,Kiehl, Oliver,Korell, Ursula,Lex, Johann
p. 1851 - 1855
(2003)
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Stereospecific, Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Allylic Pivalates to Deliver Quaternary Stereocenters
Recognizing the importance of all-carbon, quaternary stereocenters in complex molecule synthesis, a stereospecific, nickel-catalyzed cross-coupling of allylic pivalates with arylboroxines to deliver products equipped with quaternary stereocenters and internal alkenes was developed. The enantioenriched allylic pivalate starting materials are readily prepared, and a variety of functional groups can be incorporated on both the allylic pivalate and the arylboroxine. Additional advantages include the use of a commercially available and air-stable Ni(II) salt and BISBI ligand, mild reaction conditions, and high yields and ee's. The observed stereoinversion of this reaction is consistent with an open transition state in the oxidative addition step.
Cobb, Kelsey M.,Rabb-Lynch, Javon M.,Hoerrner, Megan E.,Manders, Alex,Zhou, Qi,Watson, Mary P.
supporting information
p. 4355 - 4358
(2017/08/23)

Chiral MeCBS synthesis process
The invention discloses a chiral MeCBS synthesis process. The process comprises the steps of adding 1.1-1.5 equivalent weight of methyl-boric acid in alkane solvent for back flow and water division, after the reaction is complete, lowering the temperature to 30-45 DEG C, after keeping static for filtration, lowering the filtered solution to below -20-0 DEG C, stirring and leaching out, after filtration and drying, acquiring the chiral MeCBS which is white solid with good fluidity. The processing method has the advantages of being simple in operation, being high in product purity, thus providing more choices in the current market with more available solvent types.
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Paragraph 0015; 0016

(2017/04/20)

Enantioselective Desymmetrization of Glutarimides Catalyzed by Oxazaborolidines Derived from cis-1-Amino-indan-2-ol
Enantioselective reductive desymmetrization of glutarimides has been achieved employing an oxazaborolidine catalyst derived from cis-1-amino-indan-2-ol. The reaction was found to proceed through a stereoablative process that upgraded the enantioselectivity of an intermediate hydroxy-lactam. The reaction was generally tolerant of a number of substituents in the 4-position, giving enantiomeric excesses of greater than 82%.
Kutama, Ibrahim U.,Jones, Simon
p. 11468 - 11479
(2015/12/04)

Enantioselective catalytic desymmetrization of maleimides by temporary removal of an internal mirror plane and stereoablative over-reduction: Synthesis of (R)-pyrrolam A
A highly enantioselective (>95% ee) strategy to affect the desymmetrization of a maleimide has been performed by temporary attachment to an anthracene template followed by asymmetric reduction with an oxazaborolidine catalyst. A stereoablative over-reduction process was partially responsible for the high levels of enantioselectivity. Exemplification of the strategy by stereoselective functionalization and retro-Diels-Alder reaction provided the natural product pyrrolam A.
Marsh, Barrie J.,Adams, Harry,Barker, Mike D.,Kutama, Ibrahim U.,Jones, Simon
supporting information
p. 3780 - 3783
(2014/08/05)

Rational electronic tuning of CBS catalyst for highly enantioselective borane reduction of trifluoroacetophenone
α,α,α-Trifluoroacetophenone (2), which is susceptible to noncatalytic reduction by BH3, could be reduced to chiral alcohol up to 90% ee by using electronically tuned-CBS catalyst (1) with BH3. The enantioselectivities highly correlated with the differential orbital energies between 1-BH3 adduct and 2, which were calculated by DFT method.
Korenaga, Toshinobu,Nomura, Kenji,Onoue, Kazutaka,Sakai, Takashi
supporting information; experimental part
p. 8624 - 8626
(2011/01/03)

Empirical method for predicting enantioselectivity in catalytic reactions: demonstration with lipase and oxazaborolidine
We derived a novel equation capable of predicting the degree of enantioselectivity in a catalytic reaction without any knowledge of the reaction mechanism and/or the transition-state structure, and tested the validity of this equation by changing substrates systematically in the lipase or oxazaborolidine-catalyzed reactions. A good correlation was observed between the predicted and observed E values, and the stereochemistry of the products could be predicted correctly in most cases (28 out of 30).
Ema, Tadashi,Ura, Norichika,Yoshii, Masataka,Korenaga, Toshinobu,Sakai, Takashi
experimental part
p. 9583 - 9591
(2010/01/06)

Total synthesis of (+)-azaspiracid-1. An exhibition of the intricacies of complex molecule synthesis
The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accomplished by aldol and sulfone anion methodologies. All ketalization events to form the nonacyclic target were accomplished under equilibrating conditions utilizing the imbedded configurations of the molecule to adopt one favored conformation. A final fragment coupling of the anomeric EFGHI-sulfone anion to the ABCD-aldehyde completed the convergent synthesis of (+)-azaspiracid-1.
Evans, David A.,Kvaerno, Lisbet,Dunn, Travis B.,Beauchemin, Andre,Raymer, Brian,Mulder, Jason A.,Olhava, Edward J.,Juhl, Martin,Kagechika, Katsuji,Favor, David A.
supporting information; experimental part
p. 16295 - 16309
(2009/05/08)

PROCESS FOR SYNTHESIS OF DIALKOXYORGANOBORANES
The invention relates to a process for the synthesis of dialkoxyorganoboranes, in particular to a process for the synthesis of dialkoxyorganoboranes by an ester exchange reaction. Moreover, the invention relates to a process for the synthesis of organo-oxazaborolidine catalysts (organo-CBS) and of trialkylboroxins. Furthermore, the invention relates to methods of using dialkoxyorganoboranes for the preparation of organo-CBS catalysts and in Suzuki-type coupling reactions.
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(2008/06/13)

1-AMIDO-4-PHENYL-4-BENZYLOXYMETHYL-PIPERIDINE DERIVATIVES AND RELATED COMPOUNDS AS NEUROKININ-1(NK-1) ANTAGONISTS FOR THE TREATMENT OF EMESIS, DEPRESSION, ANXIETY AND COUGH
Disclosed are NK1 antagonists having the formula: Also disclosed are uses of compounds of formula (I) for the manufacture of a medicament for treating a number of physiological disorders, symptoms or diseases, including emesis, depression, anxiety and cough.
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Page/Page column 58-59

(2010/02/06)

Asymmetric Synthesis of 4,4-Disubstituted-2-Imidazoli-dinones: Potent NK1 Antagonists
(Equation presented) A highly efficient and practical synthesis of 4,4-Disubstituted-2-Imidazolidinones utilizing a "self-reproduction of the center of chirality" strategy is described.
Reichard, Gregory A.,Stengone, Carmine,Paliwal, Sunil,Mergelsberg, Ingrid,Majmundar, Sapna,Wang, Cheng,Tiberi, Robert,McPhail, Andrew T.,Piwinski, John J.,Shih, Neng-Yang
p. 4249 - 4251
(2007/10/03)

Asymmetric synthesis of complicated bicyclic and tricyclic polypropanoates via the double Diels-Alder addition of 2,2′-ethylidenebis[3,5-dimethylfuran]
A new, non-iterative method for the asymmetric synthesis of long-chain and polycyclic polypropanoate fragments starting from 2,2′-ethylidenebis[3,5-dimethylfuran] (2) has been developed. Diethyl (2E,5E)-4-oxohepra-2,5-dienoate (6) added to 2 to give a single meso-adduct 7 containing nine stereogenic centers. Its desymmetrization was realized by hydroboration with (+)-IpcBH2 (isopinocampheylborane), leading to diethyl (1S,2R,3S,4S,4aS,7R,8R,8aR,9aS,10R,10aR)-1,3,4,7,8,8a,9,9a-octahydro-3 -hydroxy-2,4,5,7,10-pentamethyl-9-oxo-2H-10H-2.4a:7.10a-diepoxyanthracene -1,8-dicarboxylate ((+)-8: 78% e.e.). Alternatively, 7 was converted to meso-(1R,2R,4R,4aR,5S,7S,8S,8aR,9aS,10s,10aS)-1,8-bis(acetoxymethyl) -1,8,8a,9a-tetrahydro-2,4,5,7,10-pentamethyl-2H-10H-2.4a:7.10a -diepoxyanthracene-3,6,9(4H,5H,7H)-trione (32) that was reduced enantioselectively by BH3 catalyzed by methyloxazaborolidine 19 derived from L-diphenylprolinol giving (1S,2S,4S,4aS,5S,6R,7R,8R,8aS,9aR,10R,10aS)-1,8-bis(acetoxymethyl) -1,8,8a,9a-tretrahydro-6-hydroxy-2,4,5,7,10-pentamethyl-2H,10H-2.4a:7.10a -diepoxyanthracene-3,9(4H,7H)-dione ((-)-33: 90% e.e.). Chemistry was explored to carry out chemoselective 7-oxabicyclo[2,2,1]heptanone oxa-ring openings and intra-ring C-C bond cleavage. Polycyclic polypropanoates such as (1R,2S,3R,4R,4aR,5S,6R,7S,8R,9R,10R,11S,12aR)-1-(ethoxycarbonyl) -1,3,4,7,9,10,11,12,12a-decahydro-3,11-dihydroxy-2,4,5,7,9-pentamethyl-12 -oxo-2H,5H-2,4a:6,9:6,11-triepoxybenzocyclodecene-10,8-carbolactone (51). (1S,2R,3R,4R,4aS,5S,7S,8R,9R,10R,12S,12aS)-1,10-bis(acetoxymethyl) tetradecahydro-8-(methoxymethoxy)-2,4,5,7,9-pentamethyl-3,9-bis ([2-(trimethylsilyl)ethoxy]methoxy)-6,11-epoxycyclodecene-4a,6,11,12-tetrol ((+)-83), and (1R,2R,3R,4aR,4bR,5S,6R,7R,8R,8aS,9S,10aR)-3,5-bis(acetoxymethyl) -4a,8a-dihydroxy-1-(methoxymethoxy)-2,6,8,9,10a-pentamethyl-2,7-bis ([2-(trimethysilsyl)ethoxy]methoxy)dodecahydrophenanthrene-4,10-dione (85) were obtained in few synthetic steps.
Marchionni, Chiara,Vogel, Pierre
p. 431 - 472
(2007/10/03)

Production method of optically active trans-vinylsulfide alcohol
PCT No. PCT/JP96/03185 Sec. 371 Date Jun. 30, 1997 Sec. 102(e) Date Jun. 30, 1997 PCT Filed Oct. 30, 1996 PCT Pub. No. WO97/16421 PCT Pub. Date May 9, 1997A method for producing an optically active trans-vinylsulfide alcohol having the formula: wherein R1 represents an alkyl group or an aryl group, comprising the step of reducing a trans-vinylsulfide ketone with a borane reducing agent in the presence of an optically active oxazaborolidine and an additive.
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(2008/06/13)

Kinetic investigation of the reduction of pinacolone by borane catalyzed by oxazaborolidines in THF. Hydride shift as rate determining step
The kinetics of the reduction of the ketone pinacolone (P) by borane (B) catalyzed by the oxazaborolidines (OAB) (S)-1-methyl-3,3-diphenylperhydropyrrolo[1,2-c][1,3,2]oxazaborolidine and (S)-2,4-dimethyl-3,3-diphenyl-1,3,2-oxazaborolidine have been studied in THF. The findings are discussed in comparison with the kinetic results obtained previously for the same reaction using two different OABs as catalysts (C). The reaction order in the ketone P changes in the series of OABs from first-order to zero-order. This surprising behaviour excludes the addition of P to the binary complex C-B forming the ternary complex P-C-B as the rate determining step. However, the kinetic data are consistently explained if the intramolecular hydride shift in P-C-B with subsequent rearrangement leading to the complex of monoalkoxyborane and catalyst is assumed to be rate determining. The rate equations of the catalytic reactions of the four OABs, the corresponding ee values, and apparent activation energies are given.
Jockel, Holger,Schmidt, Reinhard,Jope, Helge,Schmalz, Hans-Guenther
p. 69 - 76
(2007/10/03)

Preparation of some organo-bis(diisopropylamino)boranes and their application to the synthesis of oxazaborolidines
The reactivity of ClB(NEt2)2 and ClB(NiPr2)2 towards organomagnesium or organolithium derivatives was studied.ClB(NiPr2)2 proved to be an excellent reagent for the preparation of pure boronic derivatives RB(NiPr2)2, which
Chavant, P. Y.,Vaultier, M.
p. 37 - 46
(2007/10/02)

Enantioselective reduction of ketones
Chiral 1,3,2-oxazaborolidines and tetrahydro-1,3,2-oxazaborines are effective catalysts for the borane reduction of prochiral ketones to optically active alcohols.
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(2008/06/13)

A Stable and Easily Prepared Catalyst for the Enantioselective Reduction of Ketones. Applications to Multistep Synthesis
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Corey, E. J.,Bakshi, Raman K.,Shibata, Saizo,Chen Chung-Pin,Singh, Vinod K.
p. 7925 - 7926
(2007/10/02)