With the above results in hand, we set our sights toward establishing a concise access to polysin and N-acetyl-polyveoline (Scheme 1). Preparative scale enzymatic hydroxylation of 9 provided alcohol 13 with 67% yield, which was subjected to a Smith-modified Madelung indole synthesis to provide a mixture of two adducts, 14 and 15. Treatment of this mixture with p-toluenesulfonic acid (PTSA) effected complete formation of the indole nucleus with concomitant dehydration of the tertiary alcohol at C8. In light of its potential incompatibility with acidic conditions needed for the subsequent cyclization step, oxidation of the C3 alcohol at this stage was deemed strategic and was accomplished using Albright-Goldman protocols. Following an extensive screening of Lewis acids (see Supporting Information Table ), we arrived at the use of MK-10 under microwave heating to generate a mixture of Friedel-Crafts adducts. As the C-cyclized product was observed to be unstable, an in-situ capping approach with Ac2O was devised to deliver a mixture of enol ethers 17 and 18 in 40% and 25% yields respectively under telescoped procedure. Routine saponification of 18 completed the synthesis of polysin (1) in seven steps from 7. Conversely, 17 was subjected to hydrogenation in the presence of palladium on carbon, followed by a diastereoselective reduction with K-selectride to complete the synthesis of N-acetyl-polyveoline (2) in eight steps from sclareolide (7). pressure, 17 could be reduced with just 1 atm of H2 pressure and we surmised that a strain release phenomenon might be in play to facilitate such hydrogenation under mild conditions. Synthesis of 12 from 9 was initiated by thermal opening of the latter's lactone ring to generate acid 19 (Scheme 2). A threestep Arndt-Eistert homologation of 19 afforded methyl ester 20, which was subjected to Mukaiyama hydration. Prior studies by Shenvi and co-workers in the synthesis of bilobalide showed that the reaction solvent polarity could have significant effects on the product diastereoselectivity. Based on this precedent, we undertook extensive optimization of this step by varying the reaction solvent, temperature, catalyst and reductant (see Supporting Information Table ). Unfortunately, no marked increase in diastereoselectivity was observed in all conditions tried and under the best set of conditions, a diastereomeric ratio of 1:1 at C8 was obtained. At this stage, the desired tertiary alcohol diastereomer 22 was saponified and converted to trans-syn-trans-fused lactone 12 through the use of Yamaguchi's reagent. To improve material throughput, the unwanted diastereomer 21 could be recycled into the sequence by simple methyl ester formation to regenerate 20 along with its olefin regioisomer. After three cycles, a combined 60% isolated yield of 22 could be achieved. Enzymatic hydroxylation of 12 with P450BM3 variant MERO1 L75A was next conducted on preparative scale to provide alcohol 11 in 82% yield. The structure of this compound was verified by Xray diffraction analysis, which prominently revealed the twistboat configuration of the B-ring. Drawing inspiration from the syntheses of arene-containing terpenoids by Li and co-workers, we sought to construct the central arene ring of the chrodrimanins through a 6p electrocyclization of the corresponding triene precursor. Toward this goal, the C3 alcohol of 11 was temporarily protected as the trimethylsilyl (TMS) ether and the C-ring lactone was converted to the corresponding vinyl triflate (compound 23). Sonogashira coupling of 23 with alkyne 24, synthesized in 6 steps from (R)-methyl 3-hydroxybutanoate (see Supporting Information), delivered dienyne 25 in 67% yield over 3 steps from alcohol 11. With the goal of introducing a suitable functional handle for subsequent phenol formation, an alkyne hydrosilylation approach was pursued. Previous work by Ferreira and co-workers showed that the regioselectivity of alkyne hydrosilylation is predominantly dictated by electronic effects whereby hydride delivery would take place at the sp carbon that is further away from electron-withdrawing group. Indeed, treatment of alkyne 25 with Et3SiH in the presence of catalytic Pt(DVDS) successfully provided the desired hydrosilylation product 26 as a single regioisomer.