Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• carbazole derivatives also show important applications in various functional materials [4][5][6][7]. Owing to their remarkable significance, developing convenient synthetic protocols for functionalized tetrahydrocarbazoles has attracted continual attention in synthetic and pharmaceutical chemistry [8][9][10

• ][11][12][13][14][15]. Among many well-designed strategies for the synthesis of tetrahydrocarbazoles, the direct assembly of the tetrahydrocyclohexenyl ring with readily available functionalized indoles as precursors has proven to be one of the most efficient synthetic protocols [16][17][18][19][20][21

• ][48][49][50]. On the other hand, the Diels–Alder reaction of the in situ generated indole-2,3-quinodimethanes with various dienophiles is also a powerful method for rapid construction of functionalized tetrahydrocarbazoles [51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68]. In

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• successfully developed several efficient synthetic protocols for diversely functionalized tetrahydrocarbazoles and the corresponding carbazole derivatives [41][42][43][44][45][46][47]. To further demonstrate the synthetic application of domino Diels–Alder reactions and in continuation of our aim to providing

• pointed out that the Diels–Alder reaction resulted in a complex mixture comprising four diastereoisomers of the tetrahydrocarbazoles, which was very difficult to separate. After oxidation with DDQ, the aromatized carbazole derivatives 6a–n were easily obtained as single products in good yields. The

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• attention has been paid to organic aromatic or heterocyclic hydroperoxides, probably due to their low thermal stability and high reactivity. Stable organic hydroperoxides were isolated in the early 1950s as products of autoxidation as well as catalytic oxygenation of indoles and tetrahydrocarbazoles [3][4

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• library of compounds bearing the free amino acid function at C-3 and pertaining to the class of constrained tryptophan analogues. Keywords: constrained tryptophans; Diels–Alder; indoles; tetrahydrocarbazoles; unnatural amino acids; Introduction With the term of “unnatural” amino acids, a plethora of

• NOE interactions involve cis hydrogens at positions 1 and 4 and the aromatic p-tolyl hydrogens, Figure 3. Finally, tetrahydrocarbazoles 3a,b,d and 3'a were selected as substrates to test the reactivity of our compounds under hydrolytic conditions to obtain the deprotection of indole nitrogen and the

• 2 afforded the corresponding tetrahydrocarbazoles 5a and 5b in 1:1.3 diasteroisomeric ratio (Scheme 4). As reported for the reaction between 1b and 2 in chloroform, the reaction outcome could be explained by the formation of two energetically comparable transition states (endo + exo TS) or by the

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• reaction [85]. A mild cyclization of 2-alkenylindoles 53 involving an alkenylation/acyloxylation process resulted in the formation of the 1,2,3,4-tetrahydrocarbazoles 54 bearing oxygen-containing functionalized groups (Scheme 31) [86]. Reactions were carried out by using 1,4-benzoquinone as the oxidizing