Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest. Please login or sign up for a free trial to access the full content.
37.5.1.1.2.2 Variation 2: Electrophilic Addition of C2

DOI: 10.1055/sos-SD-037-00384

Inoue, M.; Yamashita, S.Science of Synthesis, (200837598.

An intramolecular silyl-modified Sakurai reaction has been used as a powerful tool for the construction of tetrahydropyrans (Scheme 17).[‌83‌,‌84‌] Direct condensation of carbonyl compounds 92 and silyl ether 93 under the influence of trimethylsilyl trifluoromethanesulfonate produces tetrahydropyran 94 in a single step. The reaction involves the intermolecular acetalization and subsequent intramolecular nucleophilic attack of the allylsilane onto an in situ generated oxonium cation. The similar trimethylsilyl trifluoromethanesulfonate promoted annulation of silanes with aldehydes has been applied to the synthesis of a potential BC ring subunit for antitumor agent bryostatin 1 (Scheme 17).[‌85‌,‌86‌] Reaction of enal 96 with the hydroxy allylsilane 95 generates the desired bicyclic product 97 in a stereoselective manner. The stereochemical outcome is in accord with the expectation that cyclization occurs via a chair-like transition state with two alkyl chains equatorially disposed.

Meeeee 88 Meeee Meee Meeeeeee Meeee Meeeeeeeee[‌88‌,‌88‌]

eee-8,8-Meeeeeeeeeeee 8-eeeeeeeeeeeeeeeeeeeeeeeee eee ee eeeeeeee eee eeeeeeeeeee ee eeeeeeeeeee eeee eeeeee eeeee e eeeeeeeee eeeeee ee eeeeeeeeeeeeeeeeeeeeeeee eeee (Meeeee 88).[‌88‌] Meee eeeeeeee eeeeeeee eee eeeeeeeee ee eeeeeeeeeeee eeee eeeeeeeee ee eeeeeeee ee eeee eeeee 88, eeeee ee eeee eeeeeeeeeee ee ee eeeeeeeeeeeeeeee eeeeee (e.e., eee eeeeeeeee ee ee α-eeeee eeeee) ee eeeeeee eeeeeeeeeeee 88 (>88% ee).

Meeeee 88 Meøeeeee Meee Meeeeeeee Meeeeeeee ee e eee-8,8-Meeeeeeeeeeee 8-Meeeeeeeeeeeeeeeeeeeeeee[‌88‌]

Me eeeeeeeee eeeeeeee eeeeeeeee eee ee eeeeeeee ee e eeeeeee eeeeeeee (Meeeee 88).[‌88‌] Mee eeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeee eeeeeeee eeeeeeeeee ee α-eeeeeee eeeee 888 eeeeeeeee ee eeeeeeeeeeee eee eeee eeeeeeeee e eeeeee 8-eeeeee-Meee eeeeeeeeeeeee ee eeeeeee eeeeeee eeeeeeeeeeee eee. Meeeeeeeeee ee eee eeeeeeeeeeee eeee eeeee eeeeeee e eeeee eeeeeeeee eeeee ee ee eeeeeeeeeeee eeee ee eeeeeee ee eeeeeeeeeee eeeeeee ee eeee eeeeeeee eeeee 888. Meee eeeeeeee eeeeeeeeee eee eeeeeeeeeeeeeeee eeeeee eeee eeeeeeeee eeeeeeeeeeeeeeeeeeee eee eeeeee ee eeeeee ee eee eeeeeeeee ee eeeee eeeeee eeeeeeeeeeeeee eeeeeeeeeeeeeee eeeee.

Meeeee 88 Meeeeee Meeeeeeeeee ee ee α-Meeeeee Meeee[‌88‌]

Mee [8+8] eeeeeeeeeeeee eeeeeeee eeee eeeeeeee eeeeee ee e eeeeeeee eeeeee ee eeeeeeeee eeeeee eeeeeeeeeee eeee-eeeeeeee eeeeeeeee (Meeeee 88).[‌88‌,‌88‌] Mee eeeeeeeeee ee eeeeeeeeeeeee eeeeeeee eeeeee eeee eee(eeeeeeeeeeee) eeeee (888) eeeeeee e 8,8-eeeeeeeeeee eeeeeee eee ee eeeeeeeeeeee eeeee eeeeee eeeeeeee(MM) eeeeee ee eeeeeeeee/eeee(MM) eeeeeeee/eeeeee eeeeee ee e eeeeeeeee. Mee eeeeeeeee eeeee eeeeee eeee M-eeeeee 888 ee eeeeeee eee eee-eeeeeeeeeee eeeeeeeeeeeeeee 888.

Meeeee 88 [8 + 8]-Meeeeeeeeeeee Meeeeeee ee e Meeeeeee Meeee Me Meee e Meeeeeeeeeeeeee[‌88‌]

References