Cyclopropyl methanol

Cyclopropyl methanols when treated with a combination of hydrogen fluoride, pyridine, potassium hydrogen fluoride, and diisopropylamine undergo fluonnation and rearrangement to give excellent yields of homoallylic fluorides Chlorobenzene substituted cyclopropyl methanols at low temperatures leads to ring expansion to give... 

Moreover, interesting ring-formation reactions to give 7 have also been reported for substituted mclhoxyallenyl(cyclopropyl)methanols using 70% hydrogen fluoride/pyridine in combination with sodium fluoride or potassium hydrogen fluoride.82... 

Reaction of [l -(t-butyldimethylsilyl)cyclopropyl]methanol 429 with SbFs at —130 °C initially leads to formation of the 1 -(Z-butyldimethylsily I (bicyclobutonium ion 430. At — 115°C cation 430 is completely converted to the 3-endo-(t-butyldimethylsilyl)bicyclobutonium ion 428 in a few minutes. 

Starting from (Z)-undeca-l,5-dien-3-ol a biogenetic-type synthesis of (+ )-dictyopterene A was achieved using the homoallyl-cyclopropyl rearrangement as the key step for cyclopropyl formation. Solvolysis of (Z)-3-mesyloxyundeca-l,5-diene under a variety of conditions failed to give cyclopropylmethyl compounds due to the presence of the terminal double bond. In contrast, (Z)-3-mesyloxy-l-(phenylthio)undeca-5-ene (3) afforded a mixture of epimeric cyclopropyl-methanols 4 in 91 % yield. Appropriate functional group transformation eventually leads to the desired dictyopterene A. 

Methyl and ethyl cyclopropanecarboxylates readily afford (dialkyl)(cyclopropyl)methanols on treatment with alkyllithium and alkyl Grignard reagents. Lithium reagents have been used... 

The following members of this group attained practical importance l,l-bis(4-chlorophenyl)ethanol (chlorfenethol, 2), l,l-bis(4-chlorophenyl)-cyclopropyl-methanol (prochlonol, 3) and I,l-bis(4-chlorophenyl)-2,2,2-trichloroethanol (dicofol, 4). 

A simple one-pot synthesis of the bicyclobutanes (178 R = H, = R" = H or Me R = Me, R = H, R = Pr ) (> 50%) from (177) has been reported. Sequential treatment of (177) in THF at 0°C with one equivalent each of BuLi, methanesulphonyl chloride, and then BuLi again, to give (17 ), may be accomplished in 10 minutes. Terminal 7-epoxy-sulphones, on treatment with two equivalents of MeMgl, give c/s-3-phenylsulphonylcyclo-butanols thus (179) yields (180). This reaction contrasts with that of (179) with MeLi or with LiNPr 2, which gives derivatives of cyclopropyl-methanol. 

More recently, dioxaborolane derived from (RR)- +)-N,N,N, W -tetramethyltartaric acid diamide has been used as an efficient chiral controller in Simmons Smith cyclopropanation reaction of allylic alcohols to produce substituted cyclopropyl methanols in high... 

Protolysis of cyclopropyldiazomethane in water gives essentially the same product ratio as shown in (7-38) (Moss et al., 1968 a). The decomposition of the deuterium-labeled (cyclopropylmethyl)diazenolate in H2 0 afforded a slightly different ratio of cyclopropyl methanol-cyclobutanol (1.28 1) with little but extensive scumbling of D (Moss and Shulman, 1968 Moss et al., 1968). 

Matrix co-condensation of (1 -(tert-butyldimethylsilyl)cyclopropyl)methanol (Scheme 1, A (R = tert-butyl R = Me)) with SbFs onto a surface of SO2CIF/SO2F2 at -196°C yields after homogenization at -130°C a yellow solution. The initial C-NMR spectrum (Fig. 8, lower spectrum), obtained at -130°C shows two sets of signals, one set corresponding to the... 

The l-(trimethylsilyl)cyclobutyl cation is obtained by reaction of [l -(trimethylsilyl)cyclopropyl]-methanol with SbFs at -130°C. It has a hypercoordinated puckered l-(trimethylsilyl)-bicyclobutonium structure 5. Cation 5 undergoes a fast threefold degenerate methylene rearrangement (compare Fig. 2 with R = SiMe3). Averaged NMR signals are observed for the... 

Further details of the ring expansion of 1-vinylcyclopropanals and (l-hydroxy-cyclopropyl)methanols to cyclobutanols have appeared. A useful approach to cyclobutanone annelation is the addition of the readily available a-methoxyvinyl-lithium to a cyclic ketone, followed by Simmons-Smith reaction and hydrolytic rearrangement (Scheme 11) ... 

The C4H7 -cation has two different sets of three averaged methylene protons. Mono- and trideuteriated cations prepared from l-Dj-cyclopropyl-methanol [136] (Saunders and Siehl, 1980) or from l-D,-(2, 2 -D2-cyclo-propyl)methanol [137] (Roberts et al., 1984) are a mixture of stereoisomeric cations with the CHD-deuterium in the low held and in the high held methylene positions. 

High enantioselectivities are obtained using N,N,N, N -tetramethyltartaric acid diamide-derived boronate ester 32 in combination with bis(iodomethyl)zinc for asymmetric cyclopropanation of allylic alcohols. Various chiral, non-racemic cyclopropyl-methanols can be obtained in enantiomeric excesses of 91-94%. This methodology has been extended with success to the cyclopropanation of unconjugated and conjugated polyenes and homoallylic alcohols (Equation 47) [45]. 

---