- Combining Palladium and Chiral Organocatalysis for the Enantioselective Deconjugative Allylation of Enals via Dienamine Intermediates
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A catalytic enantioselective deconjugative allylation of enals is reported. A variety of enals underwent this transformation in high yield and ee, and products can be readily transformed into γ-allyl enals via a Cope rearrangement without erosion of ee. This transformation was used to install the quaternary stereocenter in (S)-bakuchiol, enabling completion of a concise formal synthesis.
- Hu, Guang,Brenner-Moyer, Stacey E.
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p. 866 - 873
(2022/01/04)
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- Regioselective molybdenum-catalyzed allylic substitution of tertiary allylic electrophiles: Methodology development and applications
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The first molybdenum-catalyzed allylic sulfonylation of tertiary allylic electrophiles is described. The method employs a readily accessible catalyst (Mo(CO)6/2,2′-bipyridine, both are commercially available) and represents the first example of the use of a group 6 transition metal-catalyst for allylic sulfonylation of substituted tertiary allylic electrophiles to form carbon-sulfur bonds. This atom economic and operationally simple methodology is characterized by its relatively mild conditions, wide substrate scope, and excellent regioselectivity profile, thus unlocking a new platform to forge sulfone moieties, even in the context of late-stage functionalization and providing ample opportunities for further derivatization through traditional Suzuki cross-coupling reactions.
- Khan, Ajmal,Khan, Shahid,Salman, Muhammad,Xu, Yaoyao,Zhang, Junjie
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p. 5481 - 5486
(2020/06/10)
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- Synthesis of Chiral Tertiary Boronic Esters: Phosphonate-Directed Catalytic Asymmetric Hydroboration of Trisubstituted Alkenes
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Highly enantioselective rhodium-catalyzed hydroboration of allylic phosphonates by pinacolborane affords chiral tertiary boronic esters. The β-borylated phosphonates are readily converted to chiral β- and γ-hydroxyphosphonates and aminophosphonates and to phosphonates bearing a quaternary carbon stereocenter. The utility of the latter is illustrated by the synthesis of (S)-(+)-bakuchiol methyl ether.
- Chakrabarty, Suman,Takacs, James M.
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p. 6066 - 6069
(2017/05/09)
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- Enantioselective Synthesis of Quaternary Stereocenters via Chromium Catalysis
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Asymmetric allylation of aldehydes with γ-disubstituted allyl halides has been achieved in the presence of a sulfonamide/oxazoline chromium complex. A variety of synthetically useful α-homoallylic alcohols with two consecutive stereogenic centers, including one quaternary carbon, can be accessed in a highly diastereoselective and enantioselective manner.
- Xiong, Yang,Zhang, Guozhu
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supporting information
p. 5094 - 5097
(2016/10/14)
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- Anti-proliferative evaluation of monoterpene derivatives against leukemia
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The cure rate of pediatric acute lymphoblastic leukemia (ALL) has significantly improved in the past thirty years, however not all patient cohorts respond well to current chemotherapy regimens. Among the high risk patient cohort is infants with MLL-rearranged (MLL-r) B-ALL, which remains dismal with an overall survival rate 35%. Our program is interested in identifying new molecular scaffolds to better understand the underlying mechanisms and ultimately provide new targeted treatments. Based on a phenotypic screen, phenolic natural products were identified as promising scaffolds for further chemical evaluation. Herein we disclose the effects of a potent anti-proliferative compound 31 against human ALL leukemia cellular models.
- Gautam, Lekh Nath,Ling, Taotao,Lang, Walter,Rivas, Fatima
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supporting information
p. 75 - 80
(2016/03/01)
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- A short synthesis of (+)-bakuchiol
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The concise enantioselective total synthesis of (+)-bakuchiol has been achieved using an asymmetric 1,4-addition to construct its all-carbon chiral quaternary center based on the induction of chirality by the (2′S)-2′-phenyloxazolidinone auxiliary, followed by a one-pot transformation under aldol reaction conditions. The synthesis was completed in four steps from (E)-geranic acid in an overall yield of 53%. Georg Thieme Verlag Stuttgart · New York.
- Esumi, Tomoyuki,Yamamoto, Chihiro,Fukuyama, Yoshiyasu
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p. 1845 - 1847
(2013/09/12)
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- A facile asymmetric synthesis of Δ3-2-Hydroxybakuchiol, Bakuchiol and ent-Bakuchiol
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A facile asymmetric synthesis of Δ3-2-Hydroxybakuchiol, Bakuchiol, and ent-Bakuchiol is described through one common intermediate bearing a chiral all-carbon quaternary carbon center, which involves stereoselectively unconjugated alkylation of the α,β-unsaturated imide bearing Evans' auxiliary, Takai-Utimoto reaction, Negishi reaction, and Heck reaction as key steps.
- Xu, Qian-Qian,Zhao, Qun,Shan, Guang-Sheng,Yang, Xi-Cheng,Shi, Qi-Yuan,Lei, Xinsheng
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p. 10739 - 10746
(2013/12/04)
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- Asymmetric construction of all-carbon quaternary stereocenters by chiral-auxiliary-mediated claisen rearrangement and total synthesis of (+)-Bakuchiol
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An asymmetric Claisen rearrangement using Oppolzer's camphorsultam was developed. Under thermal conditions, a geraniol-derived substrate underwent the rearrangement with good stereoselectivity. The absolute configuration of the newly formed all-carbon quaternary stereocenter was confirmed by the total synthesis of (+)-bakuchiol from the rearrangement product.
- Takao, Ken-Ichi,Shu, Sakamoto,Touati, Marianne Ayaka,Kusakawa, Yusuke,Tadano, Kin-Ichi
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p. 13330 - 13344
(2013/02/23)
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- Bakuchiol derivatives as novel and potent cytotoxic agents: A report
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A library of 28 compounds comprising of acyl, amino, halo, nitro, styryl and cyclized derivatives of bakuchiol have been evaluated against a panel of eight human cancer cell lines. Bioevaluation studies have resulted in the identification of potent cytoto
- Majeed, Rabiya,Reddy, Mallepally V.,Chinthakindi, Praveen K.,Sangwan, Payare L.,Hamid, Abid,Chashoo, Gousia,Saxena, Ajit K.,Koul, Surrinder
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experimental part
p. 55 - 67
(2012/04/10)
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- Synthesis of quaternary carbon stereogenic centers through enantioselective Cu-catalyzed allylic substitutions with vinylaluminum reagents
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Catalytic enantioselective allylic substitution (EAS) reactions, which involve the use of alkyl- or aryl-substituted vinylaluminum reagents and afford 1,4-dienes containing a quaternary carbon stereogenic center at their C-3 site, are disclosed. The C-C bond-forming transformations are promoted by 0.5-2.5 mol % of sulfonate bearing chiral bidentate N-heterocyclic carbene (NHC) complexes, furnishing the desired products efficiently (66-97% yield of isolated products) and in high site (>98% SN2′)- and enantioselectivity [up to 99:1 enantiomer ratio (er)]. To the best of our knowledge, the present report puts forward the first cases of allylic substitution reactions that result in the generation of all-carbon quaternary stereogenic centers through the addition of a vinyl unit. The aryl- and vinyl-substituted vinylaluminum reagents, which cannot be prepared in high efficiency through direct reaction with diisobutylaluminum hydride, are accessed through a recently introduced Ni-catalyzed reaction of the corresponding terminal alkynes with the same inexpensive metal-hydride agent. Sequential Ni-catalyzed hydrometalations and Cu-catalyzed C-C bond-forming reactions allow for efficient and selective synthesis of a range of enantiomerically enriched EAS products, which cannot be accessed by previously disclosed strategies (due to inefficient vinylmetal synthesis or low reactivity and/or selectivity with Si-substituted derivatives). The utility of the protocols developed is demonstrated through a concise enantioselective synthesis of natural product bakuchiol.
- Gao, Fang,McGrath, Kevin P.,Lee, Yunmi,Hoveyda, Amir H.
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supporting information; experimental part
p. 14315 - 14320
(2010/12/19)
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- Novel bisstyryl derivatives of bakuchiol: Targeting oral cavity pathogens
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Novel bisstyryl derivatives of bakuchiol using Heck coupling reaction as the key step were synthesized and screened against a panel of six oral cavity pathogens for their antimicrobial activity. Four compounds (9-12) showed two to fourfold and four to eig
- Mallepally V. Reddy,Niranjan Thota,Payare L. Sangwan,Pankaj Malhotra,Furqan Ali,Inshad A. Khan,Swapandeep S. Chimni,Koul, Surrinder
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experimental part
p. 3125 - 3134
(2010/09/03)
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- Synthesis and structure-immunosuppressive activity relationships of bakuchiol and its derivatives
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A series of derivatives of bakuchiol were synthesized and tested in vitro for their cytotoxicity, and inhibition of T cell proliferation and B cell proliferation. The data obtained provided preliminary structure-activity relationships of the compounds as immunosuppressive activity.
- Chen, Hongli,Du, Xiaolong,Tang, Wei,Zhou, Yu,Zuo, Jianping,Feng, Huijin,Li, Yuanchao
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p. 2403 - 2411
(2008/09/21)
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- Efficient construction of a chiral all-carbon quaternary center by asymmetric 1,4-addition and its application to total synthesis of (+)-bakuchiol
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The conjugate addition of lithium divinylcuprate to (4S,2′E)-3-(6′-TBDPS-3′-methylhex-2′-enoyl)-4-phenyloxazolidin-2-one proceeded efficiently to create a chiral all-carbon quaternary center with a high diastereoselectivity (R:S = 95:5). The absolute configuration of the newly generated chiral center was confirmed by applying this methodology to the total synthesis of (+)-bakuchiol.
- Esumi, Tomoyuki,Shimizu, Hiroyuki,Kashiyama, Akinori,Sasaki, Chizu,Toyota, Masao,Fukuyama, Yoshiyasu
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scheme or table
p. 6846 - 6849
(2009/04/07)
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- Stereoselective total synthesis of natural (S)-bakuchiol and its enantiomer
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A practical stereoselective synthesis of (S)-bakuchiol (1) and its enantiomer is reported. The important intermediate, (R)-configured β-siloxy aldehyde 5, was obtained in three steps from the easily available material geraniol (2) via the key step of Yamamoto's rearrangement of epoxy silyl ethers. (S)-Bakuchiol (1) and its enantiomer, (R)-bakuchiol (17), were finally obtained in different synthetic sequences with overall yields of 51% (ten steps) and 40% (nine steps) from geraniol (2), respectively.
- Du, Xiao-Long,Chen, Hong-Li,Feng, Hui-Jin,Li, Yuan-Chao
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experimental part
p. 371 - 378
(2009/02/07)
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- Diversity in the reaction modes of anionic and cationic stannyl reagents: γ-chloro allylstannanes as a vinyl carbene equivalent, and its application for (+/-)-bakuchiol synthesis
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Diversity in the reaction modes of anionic stannyl reagents is demonstrated by synthon representation.A new cationic stannyl reagent, γ-chloro allylstannane, has been developed as a vinyl carbene equivalent, and its utility is demonstrated by (+)-bakuchio
- Fujiwara, Jun,Sato, Tadashi
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- Diversity in the Lewis Acid-induced Reaction of Aldehydes with γ-Substituted Allylstannanes Depending upon the Substituent
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Lewis acid-induced reaction of γ-substituted allylstannanes with aldehydes proceeded at the α-, β- or γ-position, depending upon the nature of the substituents.
- Fujiwara, Jun,Watanabe, Masami,Sato, Tadashi
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p. 349 - 352
(2007/10/02)
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- Short Synthesis of (+/-)-Bakuchiol via a Geranylindium Reagent
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A short synthesis of (+/-)-bakuchiol was achieved starting with geranylindium sesquibromide and 2-(4-methoxyphenyl)acetaldehyde.
- Araki, Shuki,Bustugan, Yasuo
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p. 2395 - 2397
(2007/10/02)
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- Enantiocontrolled synthesis of natural (+)-bakuchiol
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(+)-Bakuchiol (1), an irregular phenolic monoterpene of Psoralea corylifolia L., has been first synthesized in natural forms starting from (S)-O-benzylglycidol (2).
- Takano,Shimazaki,Ogasawara
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p. 3325 - 3326
(2007/10/02)
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- BIOSYNTHESIS OF BAKUCHIOL, A MEROTERPENE FROM PSORALEA CORYLIFOLIA
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Biosynthesis of bakuchiol was examined using phenylalanine and mevalonic acid as substrates.It has been demonstrated that bakuchiol is derived from one phenylpropane (with the loss of one carbon atom) and two isoprenoid (C5) units.Key Word Inde
- Banerji, Asoke,Chintalwar, Gajanan J.
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p. 1945 - 1948
(2007/10/02)
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