82988-55-4Relevant academic research and scientific papers
Intramolecular Acylal Cyclisation (IAC) as an Efficient Synthetic Strategy towards the Total Synthesis of Erythrina Alkaloid Derivatives
Monaco, Alessandra,Aliev, Abil E.,Hilton, Stephen T.
, p. 13909 - 13912 (2015)
Compounds that comprise the erythrina alkaloid class of natural products are based on a tetracyclic spiroamine framework and exhibit a range of biological activities on the central nervous system. Herein, we report a new and efficient total synthesis of this multiple-ring system based on an intramolecular acylal cyclisation (IAC) approach. Using this methodology, the tetracyclic core was rapidly assembled over a two-step domino process catalysed by a Lewis acid. The effect of heteroatoms, substituents and ring size on the IAC has also been investigated, and the broad application of this procedure is demonstrated by the synthesis of a library of derivatives in good yields with excellent regioselectivity. Extending the diversity of the erythrina core: The tetracyclic core of the erythrina alkaloid family can be accessed through a Lewis acid mediated intramolecular acylal cyclisation (IAC) approach in two steps. Using this, heteroatoms and variation of the cyclohexyl ring produced a library of derivatives in good yields and with excellent regioselectivity.
Construction of the Erythrinane Core Skeleton via Asymmetric Catalytic Cascade Reaction of Tertiary Enamides
Zhen, Li,Tong, Shuo,Zhu, Jieping,Wang, Mei-Xiang
, p. 13211 - 13219 (2020/11/03)
We report herein an efficient cascade strategy for the rapid construction of a highly enantioenriched erythrinane core skeleton. Under the sequential catalysis of a chiral Cr(III)(salen)Cl and InCl3, cyclohexanone-derived tertiary enamides undergo an intramolecular enantioselective nucleophilic addition followed by diastereoselective Pictet-Spengler cyclization. This method is highly enantio- and diastereoselective, leading to diverse erythrina alkaloid derivatives as the sole diastereoisomer with up to 98% ee.
A convenient synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines via Pictet-Spengler reaction using titanium(IV) isopropoxide and acetic-formic anhydride.
Horiguchi, Yoshie,Kodama, Hirokazu,Nakamura, Masayoshi,Yoshimura, Tsuyoshi,Hanezi, Kaori,Hamada, Hiroko,Saitoh, Toshiaki,Sano, Takehiro
, p. 253 - 257 (2007/10/03)
A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using trifluoroacetic acid as an additional reagent. The Pictet-Spengler reaction was carried out by one pot procedure, providing a convenient and effective method for preparing various 1,2,3,4-tetrahydroisoquinolines.
One-step Synthesis of the Erythrinane Skeleton by Acid-promoted Double Cyclization of N-(Cyclohex-1-enyl)-N--α-(mehylsulphinyl)acetamide and its Derivatives
Ishibashi, Hiroyuki,Sato, Kazumi,Ikeda, Masazumi,Maeda, Hiroshi,Akai, Shuji,Tamura, Yasumitsu
, p. 605 - 610 (2007/10/02)
On being heated with toluene-p-sulphonic acid, N-(cyclohex-1-enyl)-N--α-(methylsulphinyl)acetamide (8) underwent double cyclization to give the erythrinane derivative (11), which was converted into the amide (13) by reduction with Raney nickel and into the enamide (14) by thermolysis of the corresponding sulphoxide.The double cyclization of the sulphoxide (18) gave a stereoisomeric mixture of the ether products (19a) and (19b).On treatment with Raney nickel, either (19a) or (19b) afforded a mixture of the alcohols (20a) and (20b), each o f which was oxidized with chromium trioxide-pyridine to give the same ketone (21).The sulphoxide (25) also cyclized to afford two products (26) and (27), but in low yields, which were desulphurized with Raney nickel to give the erythrinones (28) and (29), respectively.
