cus will be on the policy implications of developments in science, technology, and health, and their impact on public and private decision making. The journal will be much broader in the scope of its coverage = R* BHIpc than current publications, Smith points out, embracing such topics as arms control, government regulaLiAIH4 H+ tion, industrial competitiveness, » R*BH3Li » R*BH2 education, agricultural policy, competition in international trade, scientific and technological research Organoborane reagents and innovation, automation, secrecy in science, and health care. "We are quite excited about it," he adds. The journal will have a small staff ment of the alkylborane with hy- of about four persons, including an drogen chloride yields an alkyl- editor, managing editor, associate chloroborane, convertible to a sec- editor, and copy editor. It will pubondary amine with an organic azide, lish primarily major articles contribor alkylated to a dialkylchloroborane uted by outside authors, with subwith an olefin, which in turn fur- stantial staff editing. It also will connishes a ketone on treatment with tain a section for readers' letters and sodium methoxide, 1,1-dichloro- exchange of information and opinmethyl ether, and a hindered base. ion. An advisory board of about a With 2,3-dimethyl-2-butene, the dozen members with wide experialkylborane is converted to an alkyl- ence in science, technology, and ft'rf-hexylborane. Such an inter- health policy is now being formed. mediate, which Brown has nick- This board will advise the staff on named a thexylborane, is itself a important issues and trends, approsource of several compound types. priate authors, and the handling of For example, reaction of the alkyl- controversial issues. thexylborane with an alkene, folThe journal's editor is appointed lowed by carbon monoxide and oxi- by the presidents of the three spondation, is another route to a ketone. soring academies and serves at their 1,5-Cyclooctadiene converts an al- pleasure. The journal's staff and its kylborane to a 9-alkyl-9-borabicy- contributors will be able to draw clo[3.3.1]nonane, which is also a key upon the resources and advice of the intermediate for further syntheses. academies. However, Hammond and Stephen Stinson, New York Smith emphasize, the journal will be independent, comparable to the relationship of Foreign Affairs to its sponsor, the Council on Foreign Relations. It will not be part of azine, Science '84, published 10 times NRC, the academies' operating arm. per year, describes the new journal Different authors will express varyas "a national forum for debate, ing opinions, and some may critireaching well outside its generic cize reports or activities of the community, as Foreign Affairs is read academies. A crucial consideration for the widely outside the foreign affairs community." The journal will aim academies in deciding whether to to reach decision makers not only in go ahead with publication of the the scientific, engineering, and medi- journal was the "substantial financal communities, but also in business, cial investment involved," Smith government, academia, foundations, explains. A major market survey was made of interest in subscribing, inand other organizations. The journal will play a role not volving a mailing in January to performed by existing publications, 150,000 persons using some 30 mailnote Hammond and Philip M. Smith, ing lists. Results were "very posiexecutive officer of NAS and of the tive," he says, and "the business plan National Research Council. The fo- seems very sound." A base of 18,000
Hydroboration with isopinocampheylborane yields optically pure borane reagents \
/
lpcBH2
C=C
/
\ CH3CHO
FT BHIpc
H BHIpc | | » — C—C—
II » RftB(OCH2CH3)2
I
l p c = Isopinocampheyl
hyde displaces cv-pinene to give the optically pure diethyl alkylboronate. Lithium aluminum hydride reduces the alkylboronate to the lithium alkylborohydride, which can be converted by methanesulfonic acid to the alkylborane. Alkylboranes and alkylboronate esters serve as starting materials for conversions to other compounds without loss of optical purity. For example, alkaline hydrogen peroxide oxidation of the alkylboronate gives the alcohol, whereas reaction with lithium methoxy(phenylthio)methide and mercuric chloride yields the homologous aldehyde. Aldehydes are oxidizable to carboxylic acids or reducible to primary alcohols. Again, reaction of the alkylborane with an olefin gives a trialkylborane, which can be carbonated and oxidized to a trialkylcarbinol. Treat-
Academy journal to focus on policy A new journal, Issues in Science & Technology Policy, will be launched this September by the National Academy of Sciences, National Academy of Engineering, and Institute of Medicine. Long a dream of leaders at NAS and its two sister organizations (C&EN, July 18, 1983, page 14), the quarterly will "try to play the same role in science, technology, and health policy as the journal, Foreign Affairs, does in its area," according to the new publication's editor, Allen L. Hammond. Hammond, who also will continue to edit the American Association for the Advancement of Science's mag-
March 26, 1984 C&EN
29
Science to 20,000 subscribers is expected initially, at an annual subscription price of $24. Further marketing ef forts will be made this spring and summer. (Subscription information is available by writing Issues in Sci ence & Technology Policy, National
istry professor Roy A. Olofson at Pennsylvania State University in single-crystal x-ray studies. The McNeil researchers used sodium hexamethyldisilazide to reconvert the erythro compound to the cisoxaphosphetane and the threo com pound to the trans-intermediate. On warming of the ylide-benzaldehyde reaction mixture to —25 °C, peaks of oxaphosphetanes shrank at the same rate as the peak for triphenylphosphine oxide grew. But at the end, the ratio of cis- to transoxaphosphetane was close to 1:1. The ratio of cis- to trans-olefin pro duced was 1.5:1, which did not re flect the original 3.8:l-ratio of iso meric oxaphosphetanes. By contrast, treatment of the Wittig reagent with hexanal gave a 5.8:l-mixture of cisand trans-oxaphosphetanes, which yielded in turn a 5.8:1-mixture of cis- and trans-olefins. Maryanoff, Mutter, and Reitz con clude that in the presence of lithium, the c/s-4-phenyloxaphosphetane reacts preferentially to form olefin product, and that there is a competi tive equilibration of cis- and transoxaphosphetanes, possibly via re versible interconversion of oxaphos phetanes and starting material. Thus, they say, the relative stereochemi cal preference for cis- and transolefins in the Wittig reaction may be dictated not by what happens during reaction of aldehydes and ylides, but by what can happen to the oxaphosphetanes afterwards. D
Academy of Sciences, 2101 Constitu tion Ave., N.W., Washington, D.C. 20418.) The projections are for an eventu al circulation of 40,000, allowing the journal to reach a breakeven point in four to five years. D
Wittig reaction mechanism confirmed Chemists at McNeil Pharmaceutical, Spring House, Pa., have observed directly the cis- and trans-oxaphosphetanes long suspected to be inter mediates in the Wittig reaction [/. Am. Chern. Soc, 106, 1873 (1984)]. Their findings both confirm cur rent views of the mechanism of the reaction and shed new light on what governs amounts of cis- and transolefin products that result. Organic chemists Bruce E. Maryanoff and Allen B. Reitz worked with nuclear magnetic resonance spectroscopist Martin S. Mutter to follow phosphorus-31 spectra of re action mixtures of phosphorus ylides and aldehydes. They resolved peaks corresponding to cis- and transoxaphosphetanes at 145.8 MHz. One reason for their success is that previ ous workers were limited to the low er resolution of 40.5 MHz. Even at 145.8 MHz, the two baseline-re solved peaks are only 2.4 ppm apart. A second reason for their success is that peaks from the butylidenetriphenylphosphorane they used are farther apart t h a n those of the
ethylidene derivative other workers studied. The McNeil chemists treated b u t y l t r i p h e n y l p h o s p h o n i u m bro mide with lithium hexamethyldi silazide to generate the Wittig re agent and reacted this with benzaldehyde at —78 °C. They observed peaks for cis- and frflns-3-propyl2,2,2,4 - tetraphenyl-l,2-oxaphosphetane in a ratio of 3.8:1. They assigned peaks to the two isomers by two methods. First, they ran the reaction with sodium hexa methyldisilazide. This lithium-free technique is known to give almost entirely cis-olefin, which must come from cis-oxaphosphetane, whose sin gle peak they saw. In the second method, they added hydrogen bro mide to the reaction mixture. This reaction, discovered by organic chemistry professor Manfred Schlosser of Lausanne University, Switzer land, yielded erythro- and threo-1hydroxy-1 -phenyl - 2-pentyltriphenylphosphonium bromides in a 2.6:1 ratio. The structure of separated threo isomer was verified by chem
NMR reveals Wittig reaction intermediates H
/ ' 3 V I ' 2 V ' *2
, DΒ rΓ wΘ
© (C 6 H 5 ) 3 PCH 2 CH 2 CH 2 CH 3 6 5 3 2 2 2 3
Lithium hexamethyldisilazide foMowedby
benzaldehyde
C = C
C=C X ^ 6 ' '5
l·
/ρ Η \ Ρ_θ 1^β π 5/3; γ » J 1 / \ C6H5 CH3CH2CH2
Sodium hexamethyldisilazide
/C6H5
V
it
Hydrogen bromide
i3\^ri2wn2
Î*
(CeH5)3P-0
J_J^ Cn3Cn2CH2 Hydrogen I bromide I
·ς=± CeH5
I Sodium I hexamethyldisilazide
C6H5
H-I-OH H-|-P(CeH5)3 CH2CH2CH3
30
March 26, 1984 C&EN
(C6H5)3P=CHCH2CH2CH3
(CeH5)3P-|-H CH2Cn2Cn3
C e H 5 CHO
