Odeur et constitution IV. Sur les époxydes hydroaromatiques à odeur ambrée
TL;DR: The reduction de la lactone I, de l'hydroxyacide VI, of lacetoxyacide VII ou de lozonide de loxyde non sature XII par l'shydrure de lithium-aluminium donne le glycol II avec un bon rendement as discussed by the authors.
Abstract: La reduction de la lactone I, de l'hydroxyacide VI, de l'acetoxyacide VII ou de l'ozonide de l'oxyde non sature XII par l'hydrure de lithium-aluminium donne le glycol II avec un bon rendement.
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TL;DR: An enantio- and diastereoselective stepwise cyclization of polyprenoids induced by Lewis acid-assisted chiral Brønsted acids (chiral LBAs) and achiralLBAs and the importance of the nucleophilicity of the internal terminator in polyPrenoids for the relative stereocontrol in subsequent cyclization are demonstrated.
Abstract: An enantio- and diastereoselective stepwise cyclization of polyprenoids induced by Lewis acid-assisted chiral Bronsted acids (chiral LBAs) and achiral LBAs is described. In particular, the absolute stereocontrol in the initial cyclization of polyprenoids to form an A-ring induced by chiral LBAs and the importance of the nucleophilicity of the internal terminator in polyprenoids for the relative stereocontrol in subsequent cyclization are demonstrated. (−)-Ambrox was synthesized via the enantioselective cyclization of (E,E)-homofarnesyl triethylsilyl ether with tin(IV) chloride-coordinated (R)-2-(o-fluorobenzyloxy)-2‘-hydroxy-1,1‘-binaphthyl ((R)-BINOL-o-FBn) and subsequent diastereoselective cyclization with CF3CO2H·SnCl4 as key steps. Protection of (E,E)-homofarnesol by a triethylsilyl group increased the enantioselectivity of chiral LBA-induced cyclization and both the chemical yield and diastereoselectivity in the subsequent cyclization. The enantioselective cyclization of homo(polyprenyl)arenes posses...
114 citations
TL;DR: In this paper, a biomimetic cyclization of simple isoprenoids to polycyclic isopsrenoids using Lewis acid-assisted chiral Bronsted acids, called chiral LBAs, is described.
Abstract: Syntheses of polycyclic isoprenoids have been achieved by several groups; however, no general “biomimetic” method has yet been reported In this paper we describe the biomimetic cyclization of simple isoprenoids to polycyclic isoprenoids using Lewis acid-assisted chiral Bronsted acids, “chiral LBAs” This is the first example of a proton-induced enantioselective ene cyclization in synthetic chemistry Geranyl phenyl ethers, o-geranylphenols, and geranylacetone derivatives were directly cyclized at −78 °C in the presence of (R)-binaphthol derivatives and tin tetrachloride During the cyclization, [1,3] abnormal Claisen rearrangement often took place The enantioselectivities were up to 90% ee Compounds bearing a farnesyl group could also be cyclized under the same conditions to give the natural products (−)-Ambrox and (−)-chromazonarol These chiral LBAs recognize a trisubstituted terminal olefin enantiotopically and generate site-selective carbocations on the substrates The absolute stereochemistry of t
97 citations
TL;DR: In this paper, short and efficient syntheses of (−)-Ambrox® (12) from (−)-sclareol (1) and (+)-cis-abienol (11) are described.
69 citations
TL;DR: On a prepare par degradation du sclareol, le bicyclohomofarnesal et al. as discussed by the authors and le tetramethyl-1,1,6,10-ethyl-5-oxido-6,52-decaline.
Abstract: On a prepare par degradation du sclareol, le bicyclohomofarnesal, le bicyclohomofarnesol, et la tetramethyl-1,1,6,10-ethyl-5-oxido-6,52-decaline.
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TL;DR: On a prepare par degradation du sclareol, le bicyclohomofarnesal et al. as discussed by the authors and le tetramethyl-1,1,6,10-ethyl-5-oxido-6,52-decaline.
Abstract: On a prepare par degradation du sclareol, le bicyclohomofarnesal, le bicyclohomofarnesol, et la tetramethyl-1,1,6,10-ethyl-5-oxido-6,52-decaline.
63 citations