Catalytic, efficient, and syn-selective construction of deoxypolypropionates and other chiral compounds via Zr-catalyzed asymmetric carboalumination of allyl alcohol.
An efficient, syn-selective, all catalytic asymmetric protocol for the synthesis of alpha,omega-diheterofunctional deoxypolypropionates via Zr-catalyzed asymmetric carboalumination (ZACA reaction) was developed. The success of the method critically hinges on the one-pot conversion of unprotected allyl alcohol into TBS-protected (R)- or (S)-3-iodo-2-methyl-1-propanol (1) of 91% enantiomeric purity in 82% yield via (i) Zr-catalyzed asymmetric methylalumination, (ii) iodination, and (iii) protection with TBSCl. After zincation of 1, its Pd-catalyzed cross-coupling with various organic halides can give various organic derivatives, including 3 and 4, which can serve as key intermediates for efficient and selective syntheses of deoxypolypropionates, such as doliculide and 2,4,6,8-tetramethyldecanoic acid, and other chiral compounds, such as callystatin A. Selective monocarboalumination of 1,4-pentadiene (5 equiv) gave, after oxidation, the expected product 5, but it was 0% ee. A plausible mechanism for racemization has been proposed and experimentally supported.
Liang
Bo
B
Herbert C. Brown Laboratories of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, USA.
Novak
Tibor
T
Tan
Ze
Z
Negishi
Ei-ichi
E
D000418:Albumins / Q000737:chemistry*; D002384:Catalysis; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D020005:Propanols / Q000737:chemistry*; D011422:Propionates / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D015040:Zirconium / Q000737:chemistry
D000418:Albumins; D011108:Polymers; D020005:Propanols; D011422:Propionates; C006463:allyl alcohol; D015040:Zirconium