Caryophyllene oxide, cyclization

Scheme 25 Titanocene mediated cyclization of caryophyllene oxide...

Alcohol 2.1 is the only example of this class, and was isolated from Lactarius camphoratus (79) which belongs to Section Olentes (2). The compound is presumably the product of 1-9 cyclization of a humulene precursor. The structure and absolute configuration of this new caryophyllene oxide (2.1) was determined by a combination of spectral data and a single-crystal X-ray analysis of the p-bromobenzoate derivative 2.3. The NMR spectrum of 2.1 exhibited only two methyl signals, one of them at 51.20, together with one-proton doublet of doublets centred at 52.93, strongly suggesting the presence of the 4,5-epoxide. The C-12 methylene protons were shifted downfield (5 3.84) in the 220 MHz NMR spectrum of the acetyl derivative (2.2). Moreover,... 

---