Wieland-Gumlich aldehyde

C4HgN20 557-11-9) see Chlormerodrin Al-allyl-Wieland-Gumlich aldehyde iodide see under N -allylheminottoxiferine iodide aluminum ethylate... 

Scheme 4.2 Strychnine is readily accessed via isostrychnine or the Wieland-Gumlich aldehyde using chemistry discovered during structural elucidation/degradation studies...

Having established that the inherent selectivity of the Heck reaction would not readily allow us to access aldehyde products related to the Wieland-Gumlich aldehyde, we considered a number of other possible reaction manifolds for C20-C15 bond formation. Each substrate was accessed by deallylation of cycloadduct 104 followed by alkylation with the appropriate allylic or propargylic halide. Inspired by the extensive studies of Bonjoch, Bosch, Sole, and co-workers,... 

Scheme 4.30 Completion of a six-step linear synthesis of strychnine using a Brook rearrange-ment/conjugate addition to generate the Wieland-Gumlich aldehyde...

Hemidihydrotoxiferine I chloride contains Na—H and its IR-spectrum indicates the presence of an aldehyde group. On the basis of this and the foregoing knowledge, the structure LXVIII was proposed (86) for it, i.e., that of the 18-deoxy-Wieland-Gumlich aldehyde methochloride, and this structure was confirmed in the following manner... 

The synthesis of C-dihydrotoxiferine I has also been achieved. When the Wieland-Gumlich aldehyde (LXV) was treated with hydrogen bromide, acetic acid, and phosphorus, it yielded the 18-bromo derivative (LXXVIII R = Br), which without isolation was debrominated with zinc and acetic acid. The resulting amorphous aldehyde (LXXVIII R = Hor stereoisomer) was converted into its iVb-metho salt which was... 

A second approach, however, gave the desired compound. Caracurine V (LXXVI), prepared from the Wieland-Gumlich aldehyde, reacts with hydrogen bromide by ring-opening and bromination to give the allylic bromide (LXXIX). Reduction of this bromide with zinc and acetic acid, followed by JVb-methylation of the product, gives material in all respects identical with C-dihydrotoxiferine I (98). 

---