β Scribed by Naga Venkata Sastry Mudiganti; Sven Claessens; Norbert De Kimpe
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Asymmetric synthesis of all the four stereoisomers of cis-3,4-dihydroxy-3,4-dihydromollugins 4 and 6 and trans-3,4-dihydroxy-3,4-dihydromollugins 5 and 7 was achieved. The O-methoxymethyl mollugin derivatives were dihydroxylated to (Γ)-and (+)-cis-3,4-dihydroxy-3,4-dihydromollugin derivatives using both AD-mix-a and AD-mix-b. Deprotection of the MOM-ethers of cis-dihydroxy compounds resulted in the targeted stereoisomers (Γ)-(3R,4R)-cis-3,4-dihydroxy-3,4-dihydromollugin 4, (Γ)-(3R,4S)-trans-3,4dihydroxy-3,4-dihydromollugin 5, (+)-(3S,4S)-cis-3,4-dihydroxy-3,4-dihydromollugin 6 and (+)-(3S,4R)trans-3,4-dihydroxy-3,4-dihydromollugin 7. These routes were paved with difficulties, for example, incompatibility of the substrates with AD-mixes, the unexpected formation of trans-dihydroxy compounds and failures in deprotection protocols.
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## Abstract A short and efficient protocol for the asymmetric synthesis of __cis__β and __trans__β3,4βdihydroβ2,4,8βtrihydroxynaphthalenβ1(2__H__)βone (**1** and **2**, resp.) is described, with a phthalide annulation as the key step. Introduction of a OH substituent at position 2 was performed by