Synthesis and [4+2] Cycloaddition of (2R,2′R)‐N,N′‐Fumaroylbis[fenchane‐8,2‐sultam] (=(2E)‐1,4‐Bis[(3aS,6S,7aR)‐1,4,5,6,7,7a‐hexahydro‐7,7‐dimethyl‐2,2‐dioxido‐3H‐3a,6‐methano‐2,1‐benzothiazol‐1‐yl]but‐2‐ene‐1,4‐dione) to Cyclopentadiene

Abstract

The now corrected X-ray structure of (2R)-bornane-10,2-sultam ((À)-1a), as well as that of its already published N-crotonoyl derivative (À)-1d, were compared with those of the newly synthesized (2R)-fenchane-8,2-sultam (()-5a), as well as its N-crotonoyl derivative (À)-5d. Also the N-methyl-and N-acryloylfenchane-8,2-sultams (À)-5b,c were prepared, and both the reactivity and diastereoselectivity imparted by the new chiral auxiliary to N,N'-fumaroylbis[fenchane-8,2-sultam] (À)-5e were compared with those of (À)-1a by addition of cyclopenta-1,3-diene to (À)-5e, in various solvents and at different temperatures under TiCl 4 -mediated and uncatalyzed conditions. The determining influence of these factors is rationalized by the loss of the masked C 2 symmetry earlier attributed to camphor-derived sultams as well as transition-state dipolar stabilization by the solvent of the thermodynamically less stable syn-s-cis conformer.

Diels‐Alder Reaction of Cyclopenta‐1,3‐diene and Anthracene to bis‐Fumarates Derived from Menthol Analogues

“…The induced absolute configuration of the cycloadducts is based on the chiroptical properties in CHCl 3 of the corresponding diols (‐)‐(1 R ,2 S ,3 S ,4 S )‐ 5 , and (‐)‐(11 S ,12 S )‐ 7 ,,, (These diastereoisomers exhibit opposite chiroptical properties in either EtOH, or MeOH), as obtained after quantitative LiAlH 4 reduction of either the corresponding diesters 4 , or 6 with quantitative recovery of the prosthetic groups. The diastereoselectivity was determined on the crude cycloadducts by 1 H‐NMR analyses by integration of the vinyl protons at ca .…”

Diastereomerically pure (S)‐verbenone‐isoxazoline hybrids: Synthesis, molecular structure, Hirshfeld surface analysis, density functional theory, cytotoxic effect, and apoptosis induction

“…Certain compounds of natural origin are the primary source of chirality and are employed to prepare other enantiomerically pure substances of interest. Among the various primary chiral sources, we do mention for instance the natural monoterpenones; camphor, fenchone and their derivatives, which were widely used, their capacity of chirality transfer was reflected by the different position of the gem‐dimethyl group in each derivative [11–13]. On the other hand, reactions of monosubstituted and 1,1‐disubstituted alkenes are very regioselective favoring strongly 5‐substituted 2‐isoxazolines [10, 14–16].…”

1,3‐Dipolar Cycloadditions of a 2‐Oxoethanenitrile Oxide Derived from (2R)‐Bornane‐10,2‐sultam to Electronically Modified 4,4′‐Disubstituted Stilbenes

“…The F 2 puckering parameters for both five-membered sultam rings are in the range of those observed for both syn- conformers (90.38 [6] to 104.88 [5]) and anti-conformers (77.48 [7] [30] to 139.78 [31]). This contrasts with fenchane-8,2-sultams, which possess a modified envelope, with an S¼O(2) substituent in the pseudoaxial orientation (F 2 ¼ 252.48), despite the presence of a sterically more influent Me 2 C(3) moiety [28].…”

“…From a conformational point of view, the S¼O(2) substituent adopts a pseudoequatorial orientation due to the steric influence of the Me(9) group [28]. For both (4S,5S)-4b and (4S,5S)-4c, the S¼O(1) bond is slightly longer than the S¼O(2) bond (see Table 2 for (4S,5S)-4b, and Fig.…”