thiovanillin

[poix]

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

[Rhodium]

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%20Reactions/Chapman.htm

http://www.kcsnet.or.kr/publi/bul/bu95n5/bu95n5t15.html

http://patft.uspto.gov/netahtml/search-bool.html

can also be used with keywords such as "Newman-Kwart" or "phosphorus pentasulfide" together with "thiophenol" etc.

[Osmium]

Also known as Newman-Karnes, related to the Chapman reaction.

http://www.arkat.org/arkat/journal/Named

Reactions/Chapman.htm

Edit: ooops, Rhodium was faster...
Live long and Prosper.

[poix]

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!

[Rhodium]

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.