Synthesis and relative stereochemical assignment of the four isomeric cyclopropane-bridged tricyclo[3.2.2.02,4]nonan-6-ols

Abstract

shown by nmr and ir spectra. Purification of this product other than by glpc proved difficult. endo,exo-Tricyclo[3.2.2.02 •4]nonan-6-ol (10). A solution of 7.2 g of olefin 9 in 100 ml of tetrahydrofuran at 0°was treated with a stream of diborane generated from a solution of 4.75 g of NaBHU in diglyme and 25 ml of BF3-Et20 in 30 ml of diglyme according to the procedure previously used.28 This led to 7.31 g (87%) of a solid which upon crystallization from pentane had mp 165-168°. Glpc (B) of the original mixture indicated greater than 90% of a single alcohol, 10, nmr r 6.4 (1) m, 6.95 (1) 5, 8.15 (3) m, 8.5 (3) m, 8.88 (1) m, 8.18 (2) m, 9.8 (2) m.

Orbital-Controlled Stereoselections in Sterically Unbiased Cyclic Systems

“…On the other hand, the observed syn preference of 40a is consistent with the previous study of hydroboration of 40a with diborane by Schueler and Rhodes, who obtained a mixture of the monoalcohols (syn:anti = 74:26) upon oxidative workup. A similar magnitude of the syn preference was found (syn:anti = 73:27) in the hydroboration with a bulkier borane, 2,3-dimethyl-2-butylborane (thexyl borane) .…”

“…On the other hand, the observed syn preference of 40a is consistent with the previous study of hydroboration of 40a with diborane by Schueler and Rhodes, who obtained a mixture of the monoalcohols (syn:anti = 74:26) upon oxidative workup. A similar magnitude of the syn preference was found (syn:anti = 73:27) in the hydroboration with a bulkier borane, 2,3-dimethyl-2-butylborane (thexyl borane) . This lack of effect of the bulk of the reagent in the hydroboration of 40a is consistent with the idea that the π face of 40a is free from steric bias 157 and that the syn preference of 40a found in dihydroxylation and epoxidation is nonsterically determined …”

“…This preference is in sharp contrast to the anti preference of 41a (syn:anti = 12:88), observed under similar dihydroxylation conditions with osmium tetroxide in pyridine. While the facial selectivity of 41a has been examined previously, − that of 40a has been little studied and the topology-dependent behavior described here has not previously been documented or characterized.

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Oxymercuration-demercuration and hydroboration-oxidation of endo-tricyclo[5.2.2.02,6]undeca-3,8-diene. Stereospecific oxymercuration leading to the 4-exo-hydroxy derivative

“…(m, 12), 2.02 (s, 1, OH), 4.18 (m, 1, CHOH), 6.12 The mass spectrum of 4 was taken on the Golay GC-MS: m/e (rel intensity) 164 (26, M+), 92 (14), 91 (20), 83 (64), 82 (27), 80 (100), 79 (49), 77 (15), 41 (14), 39 (17). eadorTrieyclo[5.2.2.02 '6]undec-8-en-4-one ( 5) and endo-Tricyclo[5.2,2.02 '6]undec-8-en-3-one (6).…”

“…The third component in the product mixture was identified as 8-hydroxyendo-tricyclo[5.2.2.02,6]undec-3-ene (16)21 by the following reactions (Scheme IV). Jones oxidation of the above hydroboration product gave a mixture of ketones, 5, 6, and endotricyclo[5.2.2.02,6]undec-3-en-8-one (17),21 from which 17 could be separated on preparative VPC. The ketone 17 gave on reduction with lithium aluminum hydride followed by hydrogenation over palladium catalyst 8-endo-hydroxyendo-tricyclo[5.2.2.0Z'6]undecane (19) which was identical with the specimen prepared from 13 through hydroboration, Jones oxidation, and lithium aluminum hydride reduction (Scheme IV).…”