Full text of DOI:10.1007/BF02659538

S U M M A R Y
1. 3- Methoxy-7-methylene-3-borabicyclo [3.3.1]nonnns and
3-methoxy-l,5-dimethyl-7-methylene-3-
borabicyclo[3.3.1]nonane were converted by the action of diborans or tetraethyldiborans into 1-boraadaman-
tans and 3,5-dimethyl-l-boraadamantane, respectively.
2. l-Boraadamantans compounds possess increased complex-formlngability in comparison with trl-
alkylboranes.
scribed.
A series of complexes of 1-boraadamantane and 3,5-dimethyl-l-boraadama~ne has been de-
3. l - B o r a a d a m a ~ n s and
of the reaction products were converted into 1-hydroxyadamantane and
3,5-dlmethyl-l-boraadamantane
on carbonylatlon and subsequent oxidation
1-hydroxy-3,5-dimethyladamantane,
respectively.
L I T E R A T U R E C I T E D
Smirnov, and E. P. l~rokov'ev, Dokl. Akad. Nauk SSSB, 206, 125 (1972).
N. Smirnov, Izv. Akad. Nauk SSSR, Set. Khim., 1137 (1974).
Vasil'ev, and E. N. Safonova, Dokl. Akad. NaukBSSIR, 147, 630 (1962).
Vasil'ev, and A. Ya. Bezmenov, Izv. Akad. Nauk SSSR, Ser. Khlm., 712 (1965).
N. Smirnov, Izv. Akad. Nauk SSSR, Ser. Khim., 1672 (1972).
Vaver, and Yu. N. Bubnov, Dokl. Akad. Nauk S~qlR, 126, 575 (1959).
Chem. Soc., 84, 4715 (1962).
1.
2.
3.
4.
5.
6.
7.
8.
B . M . MfldmUov, V. N.
B . M . Mikhailov and V.
B . M . Mikhailov, L. S.
B . M . M1khailov, L. S.
B . M . Mlkhailov and V.
B . M . Mikhailov, V. A.
M . E . Hillman, J. A m .
M . E . Rillman, J. A m .
Chem. Soc., 85, 982 (1963).
9.
M . E . Hillman, J. A m . C h e m . Soc., 85, 1626 (1963).
Mikhailov, Yu. N. Bubnov, and S. I. Frolov, Izv. Akad. Nauk SSSR, Set. Khim., 2165 (1973).
B . M .
B . M . Mikhailov, Yu. N. Bubnov, and S. I. Frolov, Izv. Akad. Nauk SSSR, Ser. Khlm., 2290 C1967).
F . N . Stepanov and Yu. I. Srebrodol'skil, Zh. Org. Khlm., 2, 1633 (1966).
i0.
11.
12.
13.
Lerman, Z. Ya. Aref'eva, and G. A. Tolstikov, Zh. Org. Khim., 7, 1084 (1971).
B . M .
BOROORGANIC
C O M P O U N D S
322. THE I~EPARATION OF 1,2-OXABOEINANES
A N D 1,2- O X A B C~RE P A N E S
UDC 542.91:547.1'127
L. S. V a s i l ' e v ,
M .
M . V a r t a n y a n ,
a n d B . M . M i k h a i l o v
Among heterocycltc compounds containing boron and oxygen atoms in the ring (1,2-oxaboracyclanss)the
most accessible are the five-membered 1,2-oxxborolanss for which several simple methods of preparation
have been developed [1-4]. Higher 1,2-oxaboracyclanes are less accessible.
It was shown by us previously [3] that alkaline hydrolysis of the methyl ester of 5-bromobutyl-n-butyl-
boronic acid (I) led to 2-n-butyl-l,2-oxxborlnons 01) in ~50% yield. On more detailed investigation of the re-
action it was discovered that the moderate yield of {If) was explained by the secondary formation of a high-
boiling compohnd (lid having empirical formula CtsH40B~O3.
On oxidation of this compound with H~O2 in alka-
line m e d i u m 4-methoxy-l-butanol and n-butanol were obtained in ~1:1 ratio. Consequently, compound (Ill) is
the anhydride of 5-methoxybutyl-n-butylboronlc acid, and thus on alkaline hydrolysis of ester (I) substitution
of a bromine atom both by O H and by C C H3 had occurred although the ratio of the reaction products was
N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated
from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2308-2315, October, 1976. Original
article submitted July 30, 1975.
o.r the, i,,b~otio,, ,,,y be , , , ~ d . . ~ . , t o e d ~ • , ~ d ,.v,t,,,,. ,,, t,,,,,,,,,i,~t, in any f o , , , ~.
~
~ y ,,~,,.,. ~ t ~ t , o , , i ~ . . ~ n l ~ . fhoto~o~yi~. I
microfilming, eecoeding orothe~se, without ~ t t e n pe~ni~lon o[the publi~w. A copy o/this~ncle,, available from the puou~er ]or ~ /.~°.
]
2153

approximately unity. It is known that esters ofboroorganic acids dissolve t~ alkali with the formation of
salts of borinic acids [6-8].
Considering the e a s e with which substitution of bromine by OH and OCHs groups occurred in e s t e r (I) it
must be proposed that this is accomplished in the boranate anion (IV) by lntramolecular nucleophillc attack on
the C --Br bond by OH and OCHs groups bonded to the boron a t o m .
.
.
.
.
/
om-
m
Br(CHt)~B
0)
CH
\a
(IV)
I
OH
r
Ill
f
/
/
1/,
(III)
(V1)
\
It
(v)
It ([i)
It - .-C.l~
The methyl ester of 5-hydroxybutyl-n-butylboronic acid (V), formed as an intermediate, underwent intramolec-
ulax transesterfficatlon being converted into 2-n--butyl-l,2-oxRborinane (If). Dehydration of 5-methoxybutyl-
n-butyiboronlc acid (VI) into the anhydride (Ill) occurred in all probability on distillation in vacuum.
In the light of this m e c h a n i s m it b e c a m e obvious that to increase the yield of (If) it was necessary to ex-
clude substitution of the bromine atom by O C H 3 l.e., to start from boroorganic compounds containing no O C H 3
on the boron atom. It is convenient to use 6-bromobutyl-n-butylboronic acid (VII) or its anhydride (VIII) as
such a compound. The acid was readily formed on hydrolysis of ester (1) with water.
OH
,i, .,oB,{cv.as/
\
-an
(VII)
R
{VIII)
In practice it was shown that alkaline hydrolysis of acid (VII) or its anhydride (VIII) led to (If) in 84.5%
yield [9].
Acid (VII) may aLso be obtained by the hydrolysis of bromo-6-bromobutyl-n-butylborane
pyridinate (IX)
formed on bromination of 1-n-butylboracyclopsntane.
For the purpose of preparing (II) it is more convenient
to proceed from 1-n--butylboracyclopentane, without isolating intermediate reaction products, and this led to
significant increase in yield. Thus, (II) was obtained in 80.5% yield starting from 1-n-butylboracyclopentane
by bromination of the pyridtne complex and subsequent hydrolysis.
a
t
Br,
B
-
-
-
-
(Vll)
. ( I I )
{IX)
Similarly 2-n-bsxyl-l,2-oxaborinane (X) was synthesized in 72,3% yteid from 1-n--hexylboracyclopentane
a ' - - ~ ( x ) R'~= n-C.H,.
~
./
B
Alkaline hydrolysis of 5-bromobutylboronic acid led to 2-hydroxy-l,2-oxaborlnane (XI).
BrlCHzhB(OHh
t"oTH {xi)
~t~ (xi1)
It is interesting to note that compound (XI), being a cyclic semiester of an alkylboronic acid, may be r e d t s -
t! .led in vacuum and was obtained in analytically pure form although it also undergoes partial dehydration.
The determination of the moiscular weight of acid (xq) cryoscopically in benzene gave an enhanced value which
2154

was linked with association of (X'I) due to the formation of tntermolecular hydrogen bonds. In actual fact there
was only a wide absorption band at ~3400 cm-1 in the IB spectrum of pure (XI). In CC14 solution a band for
the free OH group appeared (3625 cm-1). Depending on the dilution of (XI) the intensity of the bond at 3625
cm -i grew and the band at ~3400 cm-i was reduced accordingly. However, even at 0.005 N solution a s m a l l
amount of compound 0(I) having associated OH groups was still noticeable.
2-n-Butyloxy-l,2-oxabortnane (XII) was obtained on esterification of (XI) with n-butanol. Hydrolysis of
bromo-5-bromohexyl-n-hexylborane led to 7-methyl-2-n-hexyl-l,2-oxaborepane (X'I/I) in 73% yield.
/
H,O, OH-
. . . .
CHICH(CHI)IB
I
A
Br
Br
II~l
{XliI)
The seven-membered 1,2-oxaborepane condensed with a benzene ring as in 2-n-butyi-6,7-benzo-l,l-oxabore-
pans (XIV) was obtained by the hydroboration of o-allylphenol with a mixture (1:1) oftetra-n-butyldiborans
and tri-n-butylborans with subsequent cyclization on distillation of the first formed diboron compound. Cycli-
zation was catalyzed by compounds containing
~ B -- H groups which were presen~ in the reaction m a s s .
OBR,
(XIV)
(XV)
B = n-C4H,
The structure of compound (XIV) was proved by oxidizing it with H20~ in alkaline medium into o-(7-hydroxy-
propyl)phenol (XV) which was isolated as the diacetate derivative.
Analysis of the GLC and PMR spectral data of compound (XIV), of its oxidation products, and of their
acetyl derivatives indicated that (XIV) was a single substance. Consequently, the boron atom of tetra-n-butyl-
diborane added exclusively to the terminal C-atom of the double bond in allylphenoL
Another method of preparing 1,2-oxaborepanes developed by us was based on the hydroboration of 2,3-
dihydropyran and of its derivatives with a tetraalkyldiborans.
According to patent data [10], on reacting diborane with an excess of 2,3-dthydropyran, subsequent
heating of the reaction products at 145-200° for 10 h, and hydrolysis with water 5-penten-l-ol was formed.
In the opinion of the authors trialkylborans (XVI) was formed in the f i r s t step and is an unusual cyclic ~-
alkoxyborane.
fl-Alkoxyethylboranes
are unstable and undergo thermal ~-flssion being converted finally into borate
esters [11]. Compound (XVI) also underwent ~-fission, tri-(5-pentenyl) borate 0fVII) was formed inthls way
and was converted without isolation into 5-penten-l-ol.
=O""'(¢hq
O
t~01 ]8
(XVl)
(XVII)
Hydroboration of borate (X'VII) led to a polymeric product on hydrolysis of which tri-(5-hydroxypentyl)borans
(X'VIII) was formed as was demonstrated by its oxidation to 1,5-psntanediol.
(XVlI) i.
~
H~O
B[(CHI)tOH]= K ~ , 3HO(CHeAOH
•
i
.
OH-
( X V l l l )
Later it was found [12] that the ~-fisslon was catalyzed by such Lewis acids as BF~. In study [13] a simple
method was developed for obtaining unsaturated alcohols from dihydropyrans and dihydrofurans using BF~.
It is interesting to note that ff diborane instead of BF3 is added to the product of hydroboration of 2,3-dihydro-
pyran (XIX) then reduction of the C -- O bond proceeded in addition to j-fission.
/BH, ,"".~s /
i'~,--S / to]
f
\
/
0
\
~ . .
BHa
\
I
0
OH
CXlX)
/ \
Hydroboration of 2,3-dihydropyran by the stoichiometric amount of diborane, catalytic fission of (XIX) in the
2155

presence of BFs etherate, subsequent hydroboratlon, and oxidation led to a 9 :I mixture of 1,5- and 1,4-pen-
tanedlols [13].
It was found by us that ff a tetr~alkyldiborane was used as ahydroborating agent inplace of diborane then
the penteny[ ester of a diallcyiboronic acid (XX) was formed.
"o"
%
BRt (XX)
I
E s t e r (XX) was converted on further hydroboration into the diboron compounds (XXI) and (XXII) which, as was
shown previously [14], readily cycltzed into 1,2-ox~orepanes and 1,2-oxaborinanes.
(x~ 'l,(B,s.~
+
~ R s
Lv,~)
~ ' / B R s
R,
%b CH,
BRs
(~tl)
R
(XXIII).
B
(XXIV)
Thus on interacting equimolar amounts of tetra-n-hexyldiborane and 2,3-dihydropyran with subsequent heating
of the reaction products at 120" for 2 h and distillation, 2-n-hexyl-l,2-oxaborepane (XXV) was obtained in 9(~
yield which according to GLC data contained ~7~o isomeric 3-methyl-2-n-hexyl-l,2-oxaborimne (XXVI).
HO(C~,~OH
HO(CH~--C~OH
&
In the case of 6-ethoxy-2,3-dihydropyran the reaction proceeded in a more complicated manner and in
place of the expected 2-n-hexyl-7-ethoxy-l,2-oxaborepane (XXIX), compound (XXV) was obtained in 70,% yield
containing ~10~ (XXVI) according to GLC data.
Rz'B
~ ) \
,.,¢r ,B m,
o
%,\ OC~H,
0
O~l-Ij
NOC~H6
I~Na'
(XXVII)
..%B
(XXVIII)
(XXIX)
R'-,n'CsH13
Evidently at the stage of forming compound (XXVII) or (XXVIII) an u-uaual ~-flssion occurred with separation
of the ethyl ester of a dialkylboronic acid (detected in the reaction products) and a pentenal or aldehyde (XXX),
respectively,whichwere converted into (XXV) on subsequent hydroboratton.
(xxvn[) _s,,aoe,m
~ o --'~s,. (xxv)
R..'B BRs'
Rs'B
(L~.X)
It is also possible that the formation of (XXV) from 6-ethoxy-2,3-dihydropyran occurred as a result of exchange
of OC~Ht by a hydrogen atom of the tetraalkyldiborane or some intermediate borane such as (XXXI).
2156

--B\
(xxxD
A s i m i l a r cleavage o f a C -- O bond occurred under the action o f diborane in tetrahydrofuran (THF) [15]. This
process takes place particularly easily if the C -- O bond is weakened by coordination with a neighboring boron
atom [13].
E X P E R IME NTA L
ALl operations with boroorganlc compounds were carried out in an atmosphere of dry nitrogen. 1-
Alkylboracyclopentanes
and the methyl esters of 5-bromobutyl-n-butyiboronic and 6-bromobutylboronic acids
were obtained by the methods in [16]. Tetra-n-butyl- and tetra-n-hexyldlborane were synthesized by passing
diborane into an ether solution of the trialkylborane [17]. o--Allylphenol was prepared by the method in [18]
and
6-ethoxy-2,3-dihydrowran was obtained from acroleln and ethyl vinyl ether according to [19].
Hydrolysis of 6-Bromobutyl-n-butylboronlc Acid Methyl Ester. Potassium hydroxide solution (20%:
172 g) was added to 5-bromobutyl-n-butyLboronlc acid methyl ester (106.1 g) and the ester dissolved. The
resulting solution was left overnight (reaction occurred ~75c7c in this time). T o complete the hydrolysis the
reaction mass was heated at 70-80° for ~2 h while following the course of the reaction by the formation of
KBr (AgNC~ titration).
The reaction mixture was acidified with dilute H2SO4, extracted with Isopentane,the
solvent removed in vacuum, and the following were isolated from the residue* (76.6 g, n~ 1.4350) by frac-
tional distillation on a H e m p e l column with metallic packing: i) 2-n-butyl-1,2-oxaborlnane (If) (29.7 g: 47,,%)
of bp 48-51" (9 ram), r ~ 1.4340 [5]; 2) 6-methoxybutyl-n-butylboronic acid anhydride (III) (30.8 g: 42~) of bp
135-137° (3 ram), n~ 1.4380. Found: C 66.04; H 12.26;
12.36;
B
6-40%.
CI8H40B2C~. Calculated:
C
66.28;
H
B
6.63%.
6-Bromobutyl-n-but~lboronic
Acid Anhydride (VIII). Bromine (57.0 g) in benzene (100 ml) was added to
a solution of 1-n-butylboracyclopentane (70.4 g) in benzene (100 ml) and kept overnight. The mixture was then
boiled for 3 h, cooled to ~20°, and water (100 mi) and tsopentane (0.5 liter) added. The organic layer was
separated, washed with water, and the solvent distilled off. Compound (VIII) (59.6 g : 81%) was isolated by
distillation of the residue and had bp 181-182° (4 ram); d42° 1.1672; nD2° 1.4735. Found: C 45.26; H 8.11;
B
5.07; Br 37.79~. C16H34BrzO. Calculated: C 45.23; H 8.07; B 5.09; Br 37.61%.
2-n-Butyl-l,2-oxaborinane CiI). a) Potassium hydroxide solution (20~c: 57.0 g) was added to (VIII) (23.7
g), the mixture was heated a t 70-80° for 2 h , then acidified with dilute H2SO4, and extracted with lsopentane.
Compound (II) (13.2 g: 84.5%) was isolated from the organic layer and had bp 70-73" (24 mm); nD2° 1.4345.
b) Pyridine (22.7 g) in benzene (50 ml) was added dropwise to a solution of freshly distilled 1-n-butyl-
boracyclopentane (35.4 g) in benzene (100 ml), 1 h later b r o m i n e (47 g) in benzene (100 ml) was added, and the
mixture was left overnight. On the following day the mixture was boiled for 2-3 h, cooled to ~20", water (50
ml) was added, the organic layer was separated, the solvent was distilled off in v a c u u m , and 20~ KOH (100
ml) was added to the r e s i d u e . The solution was heated a t 70-80° for 2.5 h, acidified with dilute H~SO4, and
extracted with isopentans. Compound (II) (32.1 g : 80.5~) was isolated by distillation and had bp 69-73° (24 ram);
nD 2° 1-4345.
Hydrogen peroxide (~25-~: 45 ml) was added dropwise to 0 to 5° to (If) (21.7g) in 20% K O H (50 ml), the
mixture was kept overnight, then extracted with ether, and the organic layer separated,
82c~) was isolated by distillation and had bp 116-119°, nD 2° 1.3995. The aqueous layer was saturated with K L
K 2 C O~ and extracted with tetrahydrofuran (THF). 1,4-Butansdlol (10.9 g: 81%) was isolated from the T H F ex-
tract by distillation and had bp 101-103° (3 ram); nD 2° 1.4455.
n-Butanol (9.1 g:
2-n-Hexyl-l,2-oxaborinane
(X). Compound (X) was obtained similarly to the preceding experiment b)
from 1-n-hexylboracyclopentane (122 g), pyridlne (65 ml), bromine (129.5 g), and 20% K O H (300 ml). It had
bp 80-83° (4 mm); nD2° 1.4403 [5].
5-Bromobutylboronic Acid. The dimethy[ ester of 5-bromobutylboronic acid (69.2 g) and water (250 ml)
were shaken vigorously until formation of a white solid andthe mixture was kept overnight. The resulting acid
was filtered off, washed with water, and dried in vacuum.
5-Bromobutylboronic acid (52.3 g: 87%) was
*Residue (5 g) in 5 N NaOH (6.4 ml) was oxidized with 3 ~ H202 (10 ml). The following were found by GLC in a
THF solution of the oxidation products: n-butanol (2 g), 4-methoxy-l-butanol (1.41 g), and 1,4-butanediol (0.97)
g). The ratio of 4-methoxybutanoI to 1,4-butansdiol was 56:44.
2157

obtained having mp 84-85° (from benzene -- hexane). Found: C 26.59; H 5.60; B 6.06; Br 43.70~. C4HI0-
BBrO z. Calculated: C 26.56; H 5.57; B 5.98; Br 44.18~.
2-Hydroxyl,lp2-o~mborinane
(XI).
5-Bromobutylboronic acid (54.3 g) and 10"~ KOH (250 g) were heated
at 60-90. for 2-3 h, the m i n u t e was acidified with dilute HzSO4, extracted with ether,and the solve-Z removed
in a water pump vacuum. Compound (XI) (28.1 g: 94.5~) was obtained in the residue as a thick liquid which
may be redistilled in an oil pump vacuum but during this (XI) underwent a significant degree of dehydration
being converted into the anhydride. Thus on distilling the residue through a Hempel column with glass packing
(XI) (8.2 E) was obtained having bp 35-40" (3 ram); nD2° 1.4455. An analytically pure specimen had bp 36-37°
(3 ram); nD2° 1.4460. Found C 47.56; H 8.88; B 10.62% tool. wt. 128. C4H~BOz. Calculated: C 48.07;
H
9.08; B 10.83~; tool. wt. 99.93. In addltion the anhydride (4.4 E) of (XI) was obtained having bp 90-93" (3
ram). Found: C 52.91; H 8.76; B 11.87~. CaHteBzC~. Calculated: C 52.83; H 8.77; B 11.9~. On subse-
quent distillation (XI) was completely converted into the anhydride.
2-n-Butyloxy-l,2-oxaborinane (XII). Potassium hydroxide solution (20~: 120 g) was added to 5-bromo-
butylboronic acid (60.2 g), the mixture was left overnight, then heated at 60-90" for 2.5 h, cooled to ~20.,
acidified with dilute HzSO4, extracted with ether, and the ether was distilled off. n-Butyl alcohol (23.8 g) and
benzene (100 ml) were added to the residue of (XI), and the water formed on esterlflcation was separated using
a Dean and Stark adapter~ Compound (XII) (34.6 g: 68~) was obtained by distillation using a Hempel column
with metallic packing and had bp 59-61" (8 ram); nD2° 1.4307. Found: C 61.61; H 10.88; B 6.79~. CsH17BO2.
Calculated: C 61.55; H 10.98; B 6.93~.
7-Meth~,l-2-n-hexyl-l,2-oxaborepane (XIII). Benzene (50 ml), pyridine (9.2 ml), and water (30 ml) were
added to bromo-5-bromohexyl-n-hexylborane which had been obtained from 7-methyl-2-n-hexyl-l,2-oxabore-
pane (25.0 g) [14] and PBrs (54.5 g) at 120-130. with subsequent distillation of the POBr s formed. The organic
layer was separated, the solvent distilled off in vacuum, 207c KOH (75 g) ~ s added to the residue, the mixture
was heated at 70-80" for 5 h, acidified with dilute H2SO4, and extracted with benzene. Compound (XIII) (9.1 g:
72.8,~) was isolated by distillation and had bp 66-68" (1 mm); nD2° 1.4410 [14].
2-n-Butyl-6~7-benzo-l,2-oxaborepane (XIV). o-Allylphenol (64 g) in absolute ether (50 ml) was added at
0~o 5" ever 2 h to a solution of tetra-n-butyldiborane (126.1 g) and tri-n-butyiborane (91.2 g) in absolute ether
(180 ml) and the mixture was left overnight. Tri-n-butylborane (175 g: 96~) was distilled off in vacuum and
methanol (25 ml) was added to the residue. Compound (XIV) (86.4 g: 9 ~ ) was isolated by distillation through
a Hempel columnwfth glass packing and had bp 85-86° (1 mm); nD2° 1.5042. Found: C 77.31; H 9.56; B 5.02,~;
tool. ~ . 200. C13HlsBO. Calculated: C 77.25; H 9.47; B 5.34,~; tool. ~ . 202.
Hydrogen peroxide (20~c: 35 ml) was added at 0 to 5" to (XIV) (15.0 g) in 3 N NaOH (28 ml) and the mix-
ture left overnight. The following day the mixture was extracted with ether, the solvent distilled off, and to
the residue [consisting of n-butyl alcohol and o-(7-hydroxypropyl)phenol] was added pyrtdine (17 ml) in ether
(50 ml) and AcCI (16.2 g), and the mixture ~ s left overnight. The following day the reaction mass was
boiled for 1 h and the solid filtered off. Ether and butyl acetate were distilled from the filtrate in vacuum and
o-(7-aceto~ypropyl)phenyl
acetate (14.1 g: 81~) was isolated having bp 128-129" (3 ram); riD2° 1.4970, which
according to GLC data contained practically no contamination by isomers. Found: C 66.13; H 6.84~%. ClsH16-
04. Calculated: C 66.08; H 6.83~.
2-n-HexTl-l,2-oxaborepane (XXV) from 2,3-Dlhydrop),ran. Dihydropyran (26.0 g) was added to a solu-
tion of tetra-n-hexyldtborane (114.4 g) in absolute ether (100 ml) and the mixture ~vas left overnight. Af~er
distilling off ether the residue was heated at 120" for 2 h. Compound (XXV) (53.7 g: 94~,~) was obtained by dis-
tlllatlon . h a Hempel column and had bp 66-68" (1.5 ram); nD2° 1.4460. Compound (XXV) was boiled for 30
rain with methanol (15 ml) (to destroy impurities containing B -- H bonds) and distilled once again. Compound
(XXV) (50.9 E: 90~) was obtained having bp 60-62° (1 ram); nD~° 1.4420 which by GLC (polyethylene glycol on
xyltte 545, 90.) contained ~7~ (XXVI). Hydrogen peroxide (~30-~: 34 ml) was added at 0-5° to the obtained
(XXV) (18.2 f) in 20~ NaOH (20 ml). The mixture was left overnight, then saturated with K=COs, and extracted
with THF. A ml~ure (8.3 g: 80~) of 93 : 7 1,5- and 1,4-pentanediols was isolated having bp 134-136" (12 ram);
nDz° 1.4498 (literature data for 1,5-pentanediol, bp 119-120. (10 ram), nDz° 1.4499 [20]).
2-n-Hexyl-l,2-o~borepane Q~XV) from 6-Ethoxy-2,3-dihydropyran. 6-Ethoxy-2,3-dihydrol~,ran (20.0 g)
in absolute ether (20 ml) was added to tetra-n-hexyidiborane (91.0 g) in absolute ether (50 ml) and the mixture
was left overnight. Ether was distilled off and the residue was heated at 120-140" for 1.5 h. A portion (42.0 g)
was withdrawn from the reaction mixture, oxidized with ~30% H20~ (7 ml), and gave a 9:1 mixture (4.57 g:
75~) of 1,5-pentanedtol and 1,4-pen~mnedtol of bp 155-156° (30 ram), nD~° 1.4496. The remainder was distilled
2158

through a Hempsl column with metallic packing taking the fraction with bp 80-100° (3 mm) (26.4 g). This f r a c -
tion was heated with absolute methanol (15 m[) and then subjected to fractional distillation. Compound (XXV)
(12.4 g: 70%) was obtained having bp 62-70° (1.5 mm); nDz° 1.4420, which contained ~10% (XXVI) according to
GLC.
S U M M A R Y
1. On alkaline hydrolysis of 6-bromobutyl-n-buty]boronic acid methyl ester replacement of the bro-
mine atom both by hydroxyl and methoxy[ groups took place.
2. Convenient methods have been developed for the synthesis of 1,2-oxaborinanes and 1,2-oxaborepanes
based on the alkaline hydrolysis of the corresponding 5-bromobutyl- or ~-bromoalky[boronic acids or their
anhydrides.
3. Hydroboration of o-allylpheno[, 2,3-dihydropyran, or 6-ethoxy-2,3-dihydropyran with tetra-n-butyl-
and tetra-n-hexyldiborane gave 2-n-butyl-6,7-benzo-l,2-oxaborepane and 2-n-hexyl-l,2-oxaborepane as ap-
propriate.
L I T E R A T U R E C I T E D
1.
2.
3.
R. Koster and G. Shomburg, Angew. Chem., 72, 567 (1960).
B . M . l~4tl.dmllov and V. A . Dorokhov, Izv. Akad. Nauk SSSR, Ser. Khim., 946 (1964).
B . M . Mfkhailov, V. A. Dorokhov, and N. V. Mostovoi, Zh. Obshch. Khtm., Problemy Organicheskogo
Sinteza, 228 (1965).
4.
5.
6.
7.
8.
B . M . Mikhailov and V. A . Dorokhov, Izv. Akad. Nauk SSSR, Ser. Khim., 1661 (1965).
B . M . Mlkhallov, L. S. Vasil'ev, and V. P. Dmitrikov, Izv. Akad. Nauk SSSR, Ser. Khim., 198 (1970).
B . M . Mlkhallov and V. A . Vaver, Dok[. Akad. Nauk SSSR, 102, 531 (1955).
B . M . Mlkhaitov and V. A . Vaver, Izv. Akad. Nauk SSSR, C~I. Khim. Nauk, 451 (1956).
B . M . Mikhailov, T. K. Kozminskaya, A . N. Blokhina, and T. A . Shchegoteva, Izv. Akad. Nauk SSSR,
Old. Khim. Nauk, 692 (1956).
9.
M.M. Vartanyan, Dissertation, Moscow (1972).
10.
J . H . Murib and C. A . Bonecutter, U. S. PatentNo. 3323146, 6-VI-1967; Chem. Abstr., 68, 78115
(1968).
11.
12.
13.
14.
B . M . Mlkhailov and A . N. Blokhlna, Izv. Akad. Nauk SSSR, Old. Khim. Nauk, 1373 (1962).
D . J . Pasto and S. R. Snyder, J. Org. Chem., 31, 2777 (1962).
G. Zwetfel and J. Plamondon, J. Org. Chem., 35, 898 (1970).
L. S. Vasil'ev, M. M. Vartanyan, V. S. Bogdanov, V. G. Kiselev, and B. M. Mlkhaflov, Zh. Obshch.
Khim., 42, 1540 (1972).
15.
16.
17.
18.
19.
20.
J. Kollonftsh, J. Am. Chem. Soc., 83, 1515 (1961).
L. S. Vasil'ev, V. P. Dmitrikov, and B. M. Mlkhailov, Zh. Cbshch. Khfm., 42, 1015 (1972).
B . M . Mikhailov, A. A. Akhnazaryan, and L. S. Vasii'ev, Dokl. Akad. Nauk SSSR, 136, 828 (1961).
Collection: Organic Reactions
[Bussiantranslation], Vol. 2, Izd. Inostr. Lit. (1950), p. 35.
R . J . Longley and W. S. Emerson, J. Am. Chem. Soc., 72, 3079 (1950).
W . H . Perkin, J. Chem. Soc., 51, 702 (1887).
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