Stereochemistry of the cyclization-rearrangement of (+)-copalyl diphosphate to (-)-abietadiene catalyzed by recombinant abietadiene synthase from Abies grandis.
[reaction: see text] Syntheses and enzymatic cyclizations of 8alpha-hydroxy-17-nor copalyl diphosphate (8a), (15R)-[15-2H1] 8b, and (15R,17E)-[15-3H1,17-2H1] copalyl diphosphate ([2H,3H] 2) catalyzed by recombinant abietadiene synthase (rAS) gave 17-nor manoyl oxide (9a), (16E)-[16-2H1] 9b, and (15S,16R)-[16-2H1,16-3H1] abietadiene ([2H1,3H1] 4), respectively. These and other results indicate that conversion of CPP (2) to abietadiene (4) occurs by anti S(N)' cyclization to a sandaracopimar-15-en-8-yl carbocation intermediate (13+, 13beta-methyl) followed by hydrogen transfer and methyl migration suprafacially on the si face of the vinyl group.
Ravn
M M
MM
Department of Chemistry, University of Illinois, Urbana 61801, USA.
Coates
R M
RM
Flory
J E
JE
Peters
R J
RJ
Croteau
R
R
D045784:Abietanes; D002384:Catalysis; D007535:Isomerases / Q000737:chemistry*; D010755:Organophosphates / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D013237:Stereoisomerism; D014197:Trees / Q000201:enzymology*
D045784:Abietanes; D010755:Organophosphates; D010616:Phenanthrenes; D011994:Recombinant Proteins; C101761:abieta-7(8),13(14)-diene; C408747:copalyl diphosphate; D007535:Isomerases; C088741:abietadiene cyclase