01-22-02 13:29
No 259346
Hello all
I thought it would be cool if we can make 2CT's from vanillin, so I searched the hive and the only thing I get was conversion of the 4-OH of vanillin with P2S5 in a post of dormouse. The discussion said that the aldehyde would be converted too and that seem bad to me.
I went to my local university and do a search for thiovanillin: I got this ref:
New key compounds in cyclotriveratrylene chemistry. Synthesis, optical resolution, absolute configuration and circular dichroism of C3-cyclotriveratrylenes with sulfur substituents. Garcia, Chantal; Andraud, Chantal; Collet, Andre. Unite Mixte Rech., Ec. Norm. Super. Lyon, Lyon, Fr. Supramol. Chem. (1992), 1(1), 31-45. CODEN: SCHEER ISSN: 1061-0278. Journal written in English. CAN 118:147280 AN 1993:147280 CAPLUS
Abstract
Vanillin and isovanillin were converted via a Newman-Kwart rearrangement to thiovanillin and isothiovanillin, which on S-methylation and subsequent redn. of the aldehyde function gave 3-methoxy-4-methylthio- (I) and 4-methoxy-3-methylthiobenzyl alc. (II), resp.
If someone can get this ref or know if the Newman-Kwart rearrangement is readily applicable it would be cool to share this info with us.
aloha P
iX
(Chief Bee)
01-22-02 13:55
No 259352
The rearrangement is pretty easy - a phenol is reacted with carbon disulfide or an alkyl derivative thereof, and the intermediate is pyrolyzed and hydrolyzed to give the thiophenol.
http://www.arkat.org/arkat/journal/Named
http://www.kcsnet.or.kr/publi/bul/bu95n5
http://patft.uspto.gov/netahtml/search-b
(Mr. Spock)
01-22-02 13:58
No 259355
Also known as Newman-Karnes, related to the Chapman reaction.
http://www.arkat.org/arkat/journal/Named
Edit: ooops, Rhodium was faster...
Live long and Prosper.
(Stranger)
01-22-02 20:06
No 259464
Thank you two
I've got one more question: is the alkylthio group more directing or less than its alkoxy counterpart? ie: if we have 4 alkylthio 3 methoxy benzaldehyde, will it put the Br at the 6(2) (like 3,4 dimethoxy bd) or at the 5 position (vanillin)?
And if we have the bare thiol at the 4 without alkyl subst, will it orient at the 5 like vanillin or at the 6?
I hope you will say what I wanna heard and if so the vanillin would be a treasure of precursor!
(Chief Bee)
01-22-02 20:18
No 259469
The bare thiol will definitely be ortho-directing (5-position). I am not sure if the outcome of a bromination of a 3-alkoxy 4-alkylthio benzaldehyde will be in the 5- or 6- position, but you could probably search the patent literature for that, or somebody else here could tell us about it.