Functional Group Protection: The Lee Synthesis of Jujuyane
A. Venkat Narsaiah of CSIR-Indian Institute of Technology, Hyderabad selectively removed one of the silyl ethers of 1, to give 2 (Tetrahedron Lett. 2021, 82, 153410. ). Andrés G. Santana of the Instituto de Productos Naturales y Agrobiología del CSIC used the proximity of the adjacent carbamate to direct the oxidative removal of one of the three benzyl ethers of 3, leading to 4 (J. Org. Chem. 2021, 86, 16736. ). Anikó Borbás of the University of Debrecen developed complementary protocols for the reduction of 5 to either regioisomer of 6 (J. Org. Chem. 2021, 86, 12973. ). Fangfang Li of Central South University and Tao Li and Wanxiang Zhao of Hunan University used diphenylphosphine to demethylate the aryl ether 7 to the phenol 8 (Org. Biomol. Chem. 2021, 19, 7633. ).
Guang Yang of Nankai University also used diphenylphosphine to convert the sulfonamide 9 to the free amine 10 (Org. Chem. Front. 2021, 8, 6182. ). Thomas Schaub of BASF showed that tributylphospine catalyzed the addition of the urethane 11 to acetylene, leading to the N-vinylated product 12 (J. Org. Chem. 2021, 86, 13041. ). Tobias Ritter of the Max-Planck-Institut für Kohlenforschung developed an alternative vinylating reagent (J. Am. Chem. Soc. 2021, 143, 12992. ). Yoshio Hisaeda and Hisashi Shimakoshi used electrolysis to convert the amine 13 to the cyanoformamide 14 (J. Org. Chem. 2021, 86, 16134. ). Yan-Ping Zhu of Yantai University coupled the amine 15 with the α-diazo β-keto ester 16, leading via Wolff rearrangement to the malonylated product 17 (J. Org. Chem. 2021, 86, 17471. ).
Jiangmeng Ren and Bu-Bing Zeng of the East China University of Science and Technology showed that povidone-iodine was an effective catalyst for converting the aldehyde 18 to the acetal 19 (Tetrahedron 2021, 92, 132250. ). Nan Li, Meng Deng and Baoming Ji of Luoyang Normal University used a Co catalyst to prepare the carboxylic acid 21 by the deprotection of the allyl ester 20 (Org. Lett. 2021, 23, 8460. ). Hua Lu of Peking University showed that in the presence of propylene oxide 23, the amino acid 22 could be converted into the N-carboxyanhydride 24 (Nature Commun. 2021, 12, 5810. ). Toyonobu Usuki of Sophia University used methanol to protect one of the three alkenes of 25, as the rearranged lactone 26 (Org. Biomol. Chem. 2021, 19, 6038. ).
The cyclooctanoid sesquiterpene jujuyane (29) was isolated from the cactus Stevia jujuyensis of Argentina. In the course of a synthesis of 29, Hee-Yoon Lee of KAIST protected one of the two alkenes of 27 as the bromo ether 28 (Org. Lett. 2021, 23, 4651. ).