Guanidine‐Catalyzed Asymmetric Trimethylsilylcyanation of Carbonyl Compounds

Kitani, Yukari; Kumamoto, Takuya; Isobe, Toshio; Fukuda, Keiko; Ishikawa, Tsutomu

doi:10.1002/adsc.200505161

Cited by 44 publications

(17 citation statements)

References 30 publications

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“…It is theoretically possible to introduce five chiral centers in the guanidine system. We found that modified guanidines prepared using our original methods [4][5][6] were effective not only in catalytic [7][8][9][10][11][12][13] but also in stoichiometric asymmetric syntheses. 14,15) The concept of modified guanidines as chiral auxiliaries in asymmetric synthesis is illustrated in Chart 2, [16][17][18] in which reactive, but resonance-stabilized, guanidinium salts 5 could be produced from guanidines 4 by quarternarization with a reagent (A-B).…”

Section: Modified Guanidines As Chiral Auxiliaries (Functionality As mentioning

confidence: 99%

Guanidine Chemistry

Ishikawa

2010

Chem. Pharm. Bull.

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Guanidines are categorized as strong organobases; however, their catalytic utility in organic synthesis has not been discussed thoroughly. The author's group has extensively and systematically studied their potential ability focusing on: 1) modified guanidines as chiral auxiliaries; 2) guanidinium ylides for aziridine formation; 3) the affinity of bisguanidine for proton and metal salts; and 4) the potential chirality of bisguanidine. Under the first topic, a variety of chiral guanidines was designed by the introduction of chirality on the three guanidinyl nitrogens, and the modified guanidines prepared using our original methods were found to be effective not only in catalytic but also in stoichiometric asymmetric syntheses. Under the second topic, the reaction of guanidinium salts carrying a glycinate function with aromatic or unsaturated aldehydes under basic conditions unexpectedly afforded aziridine-2-carboxylates, which were available as useful building blocks in organic synthesis due to their convertibility to functionalized amino acid derivatives in the ring-opening reaction, together with urea compounds recyclable to the starting guanidinium salts. The introduction of a chiral template to the guanidinium salt allowed us to expand the cyclic aziridination reaction to an asymmetric version. Under the third topic, effective complexabilty of bisguanidines with either proton or metal ions in water was observed, suggesting their possible application to the removal of toxic substances from polluted water and recovery of rare elements as material sources. Under the final topic, monomethylation or monoethylation of bisguanidine afforded a chiral product via asymmetric crystallization, indicating that bisguanidines have a potential chiral character due to the plane asymmetry.

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Section: Modified Guanidines As Chiral Auxiliaries (Functionality As mentioning

confidence: 99%

Guanidine Chemistry

Ishikawa

2010

Chem. Pharm. Bull.

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“…The reaction proceeds smoothly with 0.1 mol% catalyst loading at 25 C without solvent [36]. Treatment of aldehydes and trimethylsilyl cyanide (TMSCN) in toluene at À78 C in the presence of the catalytic amount of symmetrical bicyclic guanidine 13 smoothly afforded an (S)-excess adduct with good to moderate ee [37]. (Table 4.3) A ketonic 3-phenyl-2-butanone can work as an acceptor under the above conditions, but reactivity is low (23% yield, 39% ee).…”

Section: Cyanosilylationmentioning

confidence: 99%

“…In the kinetic resolution of 1-indanol with diphenylphosphoryl azide in dichloromethane (DCM) using modified guanidine [68], (R)-excess azide compound was produced in 58% yield with 30% ee after six hours when a C 2 -symmetrical bicyclic guanidine 13 [37] was used as a chiral auxiliary (Scheme 4.26). …”

Section: Azidationmentioning

confidence: 99%

Guanidines in Organic Synthesis

Ishikawa

2009

Superbases for Organic Synthesis

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“…The simple synthetic approach to 1,3-unsubstituted and 1-substituted 2-iminoimidazolidines was explored for new chiral superbases. 7,8 (C) Isobe et al demonstrated an alternative cyclization of modified guanidines by using appropriate 2-amino alcohols. The key step of this strategy was the substitution of the hydroxyl group through a chlorine atom catalyzed by DMC.…”

Section: Introductionmentioning

confidence: 99%

2-Cloro-1,3-Dimethylimidazolinium Chloride

Wang¹

2010

Synlett

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This feature focuses on a reagent chosen by a postgraduate, highlighting the uses and preparation of the reagent in current research 2-Cloro-1,3-Dimethylimidazolinium Chloride Compiled by Yan WangYan Wang received her B.Sc. in chemistry in 2004 and her M.Sc. in organic chemistry in 2007 from the North East Normal University, Jilin, P. R. of China. Currently, she is working towards her Ph.D. in organic chemistry at the Jilin University under the supervision of Prof. Yingjie Lin. Her research is focused on the synthesis of heterocycles in guanidinium ionic liquids.

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Guanidine‐Catalyzed Asymmetric Trimethylsilylcyanation of Carbonyl Compounds

Cited by 44 publications

References 30 publications

Guanidine Chemistry

Guanidine Chemistry

Guanidines in Organic Synthesis

2-Cloro-1,3-Dimethylimidazolinium Chloride

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