Diastereo‐ and Enantioselective Synthesis of Bisbenzannulated Spiroketals and Spiroaminals by Ir/Ag/Acid Ternary Catalysis. (19th August 2022)

• Record Type: Journal Article
• Authors: Yang, Wu‐Lin; Shang, Xin‐Yu; Ni, Tao; Yan, Hui; Luo, Xiaoyan; Zheng, Hanliang; Li, Zhong; Deng, Wei‐Ping
• Is Part Of: Angewandte Chemie. Volume 134:Number 42(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-19
• Subjects: Allylation -- Asymmetric Synthesis -- Iridium -- Spiroketals -- Ternary Catalysis; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202210207
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: We reported herein an iridium/silver/acid ternary catalytic system to access bisbenzannulated [6, 6]‐spiroketals in high efficiency with generally high diastereo‐ and enantioselectivities (up to >20 : 1 dr, >99 % ee). In this procedure, readily available o ‐alkynylacetophenones undergo cycloisomerization to generate isochromenes in situ that participate in stereoselective allylation/spiroketalization sequence with 2‐(1‐hydroxyallyl)phenols. Meanwhile, 2‐(1‐hydroxyallyl)anilines were also compatible in this cascade reaction, furnishing structurally novel bisbenzannulated [6, 6]‐spiroaminals with good diastereoselectivities (8 : 1–12 : 1 dr) and excellent enantioselectivities (98 %–>99 % ee). Moreover, experimental studies and theoretical calculations were performed to illustrate the reaction mechanism and stereochemistry. Abstract : A cycloisomerization/asymmetric allylation/spiroketalization cascade reaction of o ‐alkynylacetophenones and (1‐hydroxyallyl)phenols enabled by Ir/Ag/acid ternary catalysis was developed, affording structurally diverse bisbenzannulated [6, 6]‐spiroketals in high efficiency with mostly high diastereoselectivities and excellent enantioselectivities.