Monday, December 21, 2020
Douglass F. Taber
University of Delaware
Organocatalyzed Carbocyclic Ring Construction: The Appayee Synthesis of 9β-11-Hydroxyhexahydrocannabinol
Tianli Wang of Sichuan University used a dipeptide catalyst to mediate the construction of 3 by the addition of 2 to 1 (Adv. Synth. Catal. 2020, 362, 1966. ). Da-Ming Du of the Beijing Institute of Technology described related results (Org. Biomol. Chem. 2020, 18, 1647. ). José Alemán of the Universidad Autónoma de Madrid showed that a diamine effectively mediated the enantioselective addition of 4 to 5, leading to cyclobutane 6 (ACS Catal. 2020, 10, 5335. ).
Nicoletta Gaggero of the Università degli Studi di Milano combined 7 and 8 to make an enamine, then added that to 9, to give 10 with high stereocontrol (Org. Biomol. Chem. 2020, 18, 671. ). Takashi Washio, Shinobu Takizawa and Hiroaki Sasai of Osaka University used machine learning to optimize the phosphane-mediated Michael addition of 11 to 12, leading to 13 (Chem. Commun. 2020, 56, 1259. ). Alexander J. A. Cobb of King’s College, London showed that a tetrazolic organocatalyst cyclized 14 to yield, after reduction, the cis product 15 (J. Am. Chem. Soc. 2020, 142, 1382. ). Tohru Yamada of Keio University observed high maintenance of enantiomeric excess in the conversion of 16 to cyclopentenone 17 (Chem. Lett. 2020, 49, 60. ).
Eric N. Jacobsen of Harvard University used a urea catalyst to cyclize 18 to 19 (J. Am. Chem. Soc. 2020, 142, 6951. ). Samuel H. Gellman of the University of Wisconsin used a combination of the Jørgensen-Hayashi catalyst with a catalytic urea to convert 20 to the trans product 21 (Org. Lett. 2020, 22, 4568. ). Scott A. Snyder of the University of Chicago assembled 24 by the Jørgensen catalyst-mediated Diels-Alder reaction of 22 with 23 (Chem. Sci. 2020, 11, 2175. ). Łukasz Albrecht of the Lodz University of Technology reported similar results (Org. Lett. 2020, 22, 1813. ). Keisuke Asano and Seijiro Matsubara of Kyoto University cyclized 25 to 26 with a thiourea catalyst (Org. Lett. 2020, 22, 4710. ).
Georgios Vassilikogiannakis of the University of Crete oxidized 27 with singlet oxygen, then used the Jørgensen-Hayashi catalyst to add that ene dione to cinnamaldehyde 28, leading to cyclopentanone 29 (Org. Biomol. Chem. 2020, 18, 2817. ). James L. Gleason of McGill University catalyzed the conversion of 30 to 31 with a cyclic hydrazide (Angew. Chem. Int. Ed. 2020, 59, 253. ).
9β-11-Hydroxyhexahydrocannabinol (35) is a potent minor human metabolite of Δ9-tetrahydrocannabinol. A key step in the synthesis of 35 devised by Chandrakumar Appayee of the Indian Institute of Technology Gandhinagar was the assembly of 34 by the proline-catalyzed combination of 32 with 33 (J. Org. Chem. 2020, 85, 1291. ).
D. F. Taber, Org. Chem. Highlights 2020, December 21.