The first total synthesis and structural determination of benzopyrenomycin

The vinylogous Mukaiyama aldol reaction (VMAR) in natural product synthesis

“…35 Furthermore, a novel synthesis of a,b-unsaturated dlactones from asymmetric VMARs was also developed by this group and resulted in one-step synthesis of natural product goniothalamin (95) (Fig. 30) 36 though there was still room for enantioselective improvement.…”

The Vinylogous Aldol and Related Addition Reactions: Ten Years of Progress

“…Indeed, reaction of (Z)-configured ketene acetal 8 (3,4-Z:E > 20:1) with isobutyraldehyde (67) in the presence of TPPB, Et 2 O, and i-propanol resulted in almost exclusive formation of syn-configured vinylogous aldol (()-68 with a >20:1 dr and <1% R-aldol adduct (Scheme 13, eq 1). On the other hand, use of isomeric (E)-configured dienolate 69 (3,4-Z:E < 1:20) produced either no reaction (with TPPB) or a 1:2 mixture of R-and γ-aldol products (()-70 and (()-71 when BF 3 3 OEt 2 was employed (no diastereoselectivity observed).…”

“…Again, the Hosokawa and Tatsuta group succeeded in synthesizing agents benzopyrenomycin (127) 67 3 3 OEt 2 in CH 2 Cl 2 was the promoter of choice, while in the latter case, TiCl 4 in CH 2 Cl 2 was used. Interestingly, while the reaction involving condensed tetracyclic aldehyde 125 predominantly gave rise to syn-configured adduct 126, VMAR utilizing p-bromobenzaldehyde (128) produced the expected anti-configured vinylogous aldol 129 (96:4:<1:<1 dr).…”

The Vinylogous Mukaiyama Aldol Reaction in Natural Product Synthesis

“…Hosokawa's excessive exploitation of chiral vinylketene silyl N,O-acetal ent-136 using the VMAR protocol also culminated in the total syntheses of trichostatin D (160) [70] and benzopyrenomycin (163) [71] (Scheme 2.38). In the first instance, TiCl 4 in CH 2 Cl 2 eventually was the promoter of choice, while in the latter case, BF 3 •OEt 2 in CH 2 Cl 2 was used.…”