Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• ) moieties (Table 1, entry 7). Interestingly, using the higher coordinating solvents, DMF or DMPU, preferentially gave the opposite diastereomer, i.e., the major product being the anti-form with regard to CH3 (Cα) and OH (Cβ) moieties (anti-2a, Table 1, entries 10 and 11). For stereochemistry assignment, the

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• alkylating agent, which leads to the improved diastereoselectivity [43]. The trans stereochemistry assignment for the dialkylated products 34 follow from the observed equivalence of the acetonide methyl groups in all their proton and carbon NMR spectra. In Seebach's original studies, which established

A permutation approach to the assignment of the configuration to diastereomeric tetrads by comparison of experimental and ab initio calculated differences in NMR data

• Przemysław J. Boratyński

Beilstein J. Org. Chem. 2017, 13, 2478–2485, doi:10.3762/bjoc.13.245

• . Keywords: GIAO; NMR; stereochemistry assignment; Introduction In a stereodivergent synthesis [1] often two or more new stereocenters are created with or without control of stereochemistry and it is necessary to identify the configuration of the products. Any diastereomers exhibit disparate NMR spectra

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• ) values appears a straightforward criterion for relative stereochemistry assignment in compounds 10 derived from 2H-indolenines. As summarized in Figure 6 (see also Table S1 in Supporting Information File 1), anti-diastereomers display this coupling constant around 13 Hz, while it is in the 3-4 Hz range

• stereochemistry assignment of compounds 10 derived from 2-methylindolenines 10h–k, 10m,n is the range of 13C chemical shifts observed for the angular methyl group in their syn- and anti-diastereomers (Supporting Information File 1, Figure 7, Table S2). These findings were also verified by the available X-ray

• group between syn- and anti-diastereomers of 11a-Me in compounds 10h–k, 10m,n. Criteria for stereochemistry assignment of anti-10o. Formation of unwanted products 11 and 12 in lieu of the CCR with 9p–t. Syn/anti isomerization of compound 10e. Alternative mechanistic pathways for the CCR. Formation and