Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• stereocontrol (Scheme 1b) [24]. In 2023, Zeng et al. reported the first example of a chromium-catalyzed spirocyclization between anilines and cyclobutanones, providing direct access to medicinally relevant cyclobutane-annulated and structurally constrained spirotetrahydroquinoline (STHQ) scaffolds [25]. Given

• moderate to good yields. Subsequently, we investigated the scope of cyclobutanones and their analogues in the domino cyclization to access structurally diverse spirotetrahydroquinoline derivatives (Scheme 2). Heterocyclic analogues incorporating oxygen or sulfur atoms within the four-membered ring proved

• to be compatible substrates, affording cyclo-O/S-containing STHQ derivatives 3ab and 3ac in good yields. Additionally, ester-functionalized cyclobutanones exhibited smooth reactivity with aniline, enabling the synthesis of substituted STHQ motifs 3ad and 3ae in satisfactory yields. Notably, when

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• with hydrobromic acid and zinc bromide leads to 1-arylthiocyclobutenes 7 [13] and 2-alkyl-substituted cyclobutanones 8 [11][12], respectively. Treatment of 6 with hydrobromic acid and zinc bromide in the presence of a thiophenol provides the 1,1-di(arylthio)cyclobutane 9 which, upon reaction with

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• % and 9% yields, respectively (Scheme 30) [273]. However, in order to perform the asymmetric oxidation of 3-substituted cyclobutanones 96a–f to the corresponding lactones 97a–f (Table 7) [274], it is necessary to employ chiral Brønsted acids [274][275][276][277], organocatalysts [278][279] or enzymes

Alkoxide-induced ring opening of bicyclic 2-vinylcyclobutanones: A convenient synthesis of 2-vinyl-substituted 3-cycloalkene-1-carboxylic acid esters

• Xiufang Ji,
• Zhiming Li,
• Quanrui Wang and
• Andreas Goeke

Beilstein J. Org. Chem. 2012, 8, 650–657, doi:10.3762/bjoc.8.72

• cyclobutanones 4 undergo stereoselective ring openings by the action of alkoxide ions (t-BuO− or MeO−) to produce novel vicinally disubstituted cycloalkene derivatives 5 and 6 in moderate to high yields. The ring cleavage usually occurs with complete regioselectivity. The accessibility of γ,δ-unsaturated ester

• or acid derivatives makes this transformation a good supplementary method for the well-established Johnson–Claisen rearrangement. Keywords: alkoxide; cyclobutanones; esters; fused ring systems; ring opening; Introduction A great variety of methods are available for the synthesis of cyclobutane

• . In particular, due to their facile accessibility [3][4][5][6][7][8] and expeditious ring transformations, the use of cyclobutanones as extremely versatile and useful starting materials or intermediates in the construction of carbon skeletons has flourished over the past three decades [9][10]. In

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• expansions involving oxygenated functions 1.1 Cyclopropanols and cyclobutanols Substituted cyclobutanones [13][14][15] and cyclopentanones [16][17][18] constitute valuable building blocks in organic synthesis due to their rich chemistry. In addition, they are common motifs in numerous natural products. Among

• 19 can be transformed into cyclobutanones 20 with absolute stereocontrol at the quaternary stereogenic center generated during the reaction by the use of a binuclear chiral gold-phosphine complex, as shown in Scheme 6 [22]. Bicyclic cyclopentanones can also be obtained in a related transformation